This should get a more extensive answer, but what I could find in The Economist:
Voters are ambivalent about the newcomers. In a survey in 2016, 63% told CBOS, a pollster, that Ukrainians are good for the economy. But a similar number said the government should restrict the flow of migrants from the east. Meanwhile, government ministers invoke the influx of Ukrainians as an excuse for defying EU demands to accept refugees from the Middle East, saying their country is already shouldering the burden of migration from a war-torn country. In fact, most of the Ukrainians are economic migrants from the country’s peaceful areas. Only a few hundred apply for refugee status in Poland each year, and in 2016 just 16 received it.
In an interesting twist:
A newly established Ukrainian Workers’ Trade Union is asking for amnesty to the Polish government and Polish MPs for Ukrainians working illegally in Poland. The Union proposes a regulation that would give the right to legally stay and work in Poland for all those Ukrainian citizens who register at the province governor’s office of their place of residence. [...]
The demand is supported by the two largest Polish trade unions (OPZZ and NSZZ Solidarność). Activists are also trying to get support from the Polish Ombudsman, the State Labour Inspectorate and the Council of Ministers. The Polish government has already promised to look at the proposal after it is officially submitted to the Ministry of Family, Labour and Social Policy.
I'm guessing the Polish unions support the proposal because illegal workers get paid even less than other Ukrainians, so they drive the pay (even further) down. There's one other article which mentions this issue of wage increase being held back in Poland due to Ukrainian supply, but without clear attribution as to whom expressed this concern:
the average wage of Ukrainians is less than € 500 / month in the Warsaw metropolitan area, which is the region with the highest wages, and it is likely that the overall increase of wages would be higher in Poland without the competition of these foreign workers. This is why some voices are raised in Poland against the massive nature of this temporary immigration from Ukraine, even if the linguistic and cultural proximity between the two peoples greatly facilitates integration and if the presence of Ukrainians does not bring any specific tension. Moreover, the Poles understand quite easily the situation of Ukrainians who emigrate in search of a better salary, since they are traditionally a people of emigrants.
Actually a better written article more clearly attributes this concern to Polish trade unions:
The large OPZZ confederation wants the new trade union to help to protect Ukrainian workers by ensuring that the rules of the International Labour Organization and Poland’s minimum labour standards are applied. In practice, the OPZZ hopes to put an end to competition from Ukrainian workers prepared to work for very low wages, which puts downward pressure on the wages of Polish workers.
In fact it looks like the Ukrainian workers' union was set up with help form the Polish unions (same source):
For the first time a Polish trade union confederation, the OPZZ, has helped to establish a trade union for migrant workers in Poland. In May 2016 it set up a union for Ukrainian workers in Poland with a view to organising and defending the rights of the numerous immigrant workers from Ukraine. The OPZZ thus hopes to combat undeclared work and social dumping in Poland.
Marx would be proud. :-)
I also (finally) found something on the political level:
Poland’s “eastern policy” has two broad traditions that crystallised in the interwar period.
The first (called pilsudczykowska, after Pilsudski, the leader of the independent left) assumes supporting Ukraine to counter the risk of expansion of Russian influence closer to Polish territory. The other one (called endecka, from the nationalist movement of National Democracy) treats Ukrainians as eternal historical enemies against whom even alliance with Russia is acceptable. Since Ukraine gained independence in 1991, the Polish political scene has been dominated by a Pilsudski-school consensus. But today, Poland’s “National Democracy” tendency is also making itself heard.
The Prawo i Sprawiedliwosc [Law and Justice] party itself is not decidedly anti-Ukrainian. Officially, it supports Ukraine in its conflict with Russia (although declarations are not followed by concrete action), and there are no significant clashes on the subject of Volhynia between Warsaw and Kiev. Members of the PiS government are also aware of the benefits of the immigration from Ukraine, which they sporadically express in the media. According to the Polish Union of Entrepreneurs, over the next 20 years Poland will need an additional five million people in order to maintain the current level of economic growth.
However, fearing its most radical voters, Prawo i Sprawiedliwosc does not want to appear enthusiastic towards Ukraine or Ukrainian workers. The anti-Ukrainian fraction in the party is also growing stronger. The situation is slightly similar to that in Hungary, where the ruling right-populist party Fidesz was forced to adopt the agenda of the far-right Jobbik party in order to prevent the strengthening of the opposition from the right.
In this sense, Prawo i Sprawiedliwosc does not inflame anti-Ukrainian sentiments itself, but turns a blind eye. As xenophobic attacks are not condemned by the members of the ruling party, it creates conditions under which such hatred can thrive. And such incidents, as the Polish Ombudsman alarms, occur growingly often, even though Poles' attitude towards Ukrainians is, on the whole, much better than their sentiments towards Arabs or Roma people.
The above is from a Polish journalist, whom generally don't dig PiS much (and vice-versa)...