Not all AOVs showing up in EXtractoR

I'm rendering multi-layer EXRs from Houdini and have a large number of LPE tag-split lighting passes. When I bring them into AE, only about 2/3 of the actual passes are showing up in EXtractoR. I know the AOVs are there--they show up fine in Nuke. The ones that do and don't show up seem arbitrary--some of the LPE-tagged passes show up, some don't. It's not an alphabetical issue--it's not just the last alphabetically showing up in the list. Why does EXtractoR not show all available passes? Is there a limit to how many it can accommodate and I just need to handle that part in Fusion or Resolve or somewhere else? ProEXR is no longer needed, right? Or is it?