Had this issue forever. I use Infuse infrequently, and when I do, it won’t playback my Plex media (although it does talk to the library because titles I just added today are shown in Infuse) and I get the common HTTP error. Normally I have to remove the Plex share and add it back in, but I read there is a way to refresh the Plex token by just logging into Plex (in Infuse).
For the life of me, I cannot find where/how to do that in the Infuse app for iOS (or iPadOS).
Currently on 8.5.3 of Infuse Pro.
Thanks for any help here.