Given how Zelensky was willing to agree with everything that Trump was saying in that conversation, it shouldn't be too surprising that Zelenskiy agreeing with Trump in public too doesn't seem terribly genuine.
Zelensky was fawning to Trump to such an extent that EU decided to comment:
According to the White House’s rough transcript of the call, Trump said the United States has been “very very good to Ukraine” and slammed European countries for allegedly not doing enough, saying “Germany does almost nothing for you.”
Zelensky replied by saying Trump was “absolutely right. Not only 100 percent, but actually 1000 percent.” He praised Trump and went on to say he met both German Chancellor Angela Merkel and French President Emmanuel Macron and told them: “They are not working as much as they should work for Ukraine.”
Those comments were not well received in Europe.
“To say that I consider this to be incomprehensible would perhaps be a mild way to put it,” Elmar Brok, who was recently appointed special adviser on Ukraine for outgoing European Commission President Jean-Claude Juncker, told The Washington Post on Thursday.
Trump’s comments, Brok said, were “factually completely inaccurate.”
Brok pointed to a free-trade agreement between the European Union and Ukraine, which he said has boosted Ukrainian exports to the E.U. in recent years. The United States has not struck a similar agreement with Ukraine.
Since 2014, the E.U. and European financial institutions have also mobilized more than $16 billion in loans and grants for Ukraine, E.U. officials said Thursday.
“In these five years, we have put together for Ukraine the largest support package in the history of the European Union,” Carlos Martin Ruiz de Gordejuela, a spokesman for the European Commission, said at a news conference. He declined to comment specifically on the July call between Trump and Zelensky.
Also, it's not entirely correct that "this is not getting any attention". When Zelensky declared (again) at a press conference on Oct 10 that there was "no blackmail", his statement received widespread coverage on that very day. And Zelensky's Oct 10 "no blackmail" statement was covered again more recently e.g. by the BBC on Oct 15 or in an Oct 23 article in NYT both in the context of impeachment. So while the press that does not dig Trump is not putting this on their front pages every day, they are not completely ignoring it either. But there are only so many times something like that is worth asking or worth reporting.
Of note is that in Zelensky's more detailed account, he says it wasn't blackmail because he personally didn't know at the time of the Trump call (July 25) that military aid was being withheld by the US. Zelensky maintains that he personally only found out about the aid being withheld on September 1.
On the other hand:
President Trump tells his acting chief of staff, Mick Mulvaney, to hold back almost $400 million in military aid to Ukraine at least a week before his phone call with Ukraine’s President Zelenskyy, the Washington Post reports.
So yeah, it's possible for Zelensky to be truthful about not feeling blackmailed or pressured (assuming his account of when he found out about the aid being withheld is truthful) and, at the same time, it's possible that there was a [clumsy] attempt to blackmail him, but he just didn't get the (full) message (but only the Biden-investigation request part) on the phone call.
And more recently (Oct 24) AP reported that sources close to Zelensky related on condition of anonymity that he was worried of Biden-related pressure as early as May 7, before he even took office:
More than two months before the phone call that launched the impeachment inquiry into President Donald Trump, Ukraine’s newly elected leader was already worried about pressure from the U.S. president to investigate his Democratic rival Joe Biden.
Volodymyr Zelenskiy gathered a small group of advisers on May 7 in Kyiv for a meeting that was supposed to be about his nation’s energy needs. Instead, the group spent most of the three-hour discussion talking about how to navigate the insistence from Trump and his personal lawyer Rudy Giuliani for a probe and how to avoid becoming entangled in the American elections, according to three people familiar with the details of the meeting.
They spoke to The Associated Press on the condition of anonymity because of the diplomatic sensitivity of the issue, which has roiled U.S.-Ukrainian relations.
The meeting came before Zelenskiy was inaugurated but about two weeks after Trump called to offer his congratulations on the night of the Ukrainian leader’s April 21 election.
The full details of what the two leaders discussed in that Easter Sunday phone call have never been publicly disclosed, and it is not clear whether Trump explicitly asked for an investigation of the Bidens.
The three people’s recollections differ on whether Zelenskiy specifically cited that first call with Trump as the source of his unease. But their accounts all show the Ukrainian president-elect was wary of Trump’s push for an investigation into the former vice president and his son Hunter’s business dealings.