A couple of tweets from oil market journalist, Amena Bakr
States that have not achieved their quotas in May will be asked to "make up for it" in the coming months - opec sources
Bottom line is: compliance is key and before moving forward with an extension of the opec plus pact, Saudi Arabia and Russia want to make sure all member states are doing their part.
On the part of asking member to 'make up for it', that is almost certainly not going to work. If they get to an agreement to extend the cuts for 1-2 months, nobody would want to miss out on pumping more when prices are able to keep at these "better" levels compared to April.