idp users having authentication issues on some devices

[Rod Widdowson]

>  Any info on
> this issue would be very helpful.

Are you using the back channel? (for instance for attribute queries).  That might be the case if it is not configured for attribute
push.  If that was the case and if it was serving that channel with a non supported <something> then this *might* be the answer (I'm
not well versed with that code).