Yes, it seems that intervention in Ukraine is one of the major reasons that is a road-block to Russia's OECD membership (OECD statement, 2014):
13/03/2014 - Further to a meeting of its governing Council on 12 March
2014, the OECD has postponed activities related to the accession
process of the Russian Federation to the OECD for the time being.
At the request of the Members of the Organisation, the Secretary
General has informed the Russian Federation accordingly.
Deutsche Welle provides even more insight for this matter:
The suspension of accession talks with Moscow came amid mounting
international pressure on Russia over its role in the Ukraine crisis,
which is set to escalate at the weekend when pro-Russian forces in
Crimea hold a referendum aimed at seceding from Ukraine.
OECD membership is largely symbolic, but involves a series of
examinations on OECD standards in areas such as democratic freedoms,
tax and environment laws, as well as accounting and statistics rules.