I've contacted my reseller, but I'm outside of any return policy they offer. I've been working with Ultimaker technicians to figure this out. The respooling is a mystery to everyone, but when dis-assembling the Material Station, I saw a wire for the respooling function had some torn insulation, so maybe that's the issue? I re-seated that connection anyway, but haven't been able to print a job to see if that solved anything (Still getting ER56 when I try to use the Material Station). While the Material Station was taken apart, I disconnected and then reconnected all of the RFI readers, which seems to have resolved the detecting issue.
The PVA was put into the Material Station brand new. I now suspect the original packaging for that roll was compromised. I'm going to try a new roll of PVA when I get the Material Station back and running. And we don't change material often. Extruder 2 is almost exclusively PVA, while Extruder 1 is 80% Tough PLA, 15% TPU, and about 5% experimental (PC, UltraFuse, Nylon). I'd say we do 2-3 material changes a week.
I've arranged with the technicians to have the Material Station sent in for maintenance. I still get an ER56, even after unclogging the merger points (Which did, in fact, have broken PVA wedged in there)