I don't think you have a MIGX problem just parsing problem. How big of a jump in MODX upgrade did you do? There has been changes to caching and how nested snippets work.
Could be that previous developer modified pdoTools - pdoResources to read TV values like "eendate" and now you have to use the prepareTv etc or replace the where with migx placeholder...
I think, he doesn't pull resources at all with his pdoResources-call.
thus my suggestion to try migxLoopCollection instead.
Wow, thanks Bruno and sorry to the original poster for adding confusion to this problem!!
what happens with a call like that: