I have done minimal testing, and here are the results:
Store: Google Play
Unity Purchasing Package version: 3.2.1
Unity Version: 2020.3.7f1
There doesn't seem to be any errors if you upload a build that changes a product's definition from Consumable to Non-Consumable.
If you purchased the Consumable version before the conversion, Unity will not be able to ...
Ok; I've never done Oculus development but I stumbled upon their Unity lifecycle documentation while researching the same question, figured I'd post it here as one more step towards solving the mystery. From there (see original page for full details; I'm intentionally filtering this down to standard Unity messages only):
HMD unmount and mount with a delay
EDIT: Since writing this answer, the problem has reappeared. Extremely odd how it worked for a few builds. Then all I did was change the music from one file to another, build again and suddenly the exact same problem process has resurfaced.
(If somebody did wish to see the project, pending me adding it to Github. I zipped it in it's current state, 2 part ...