Yesterday I was in Aylesbury, where I bought an Off-Peak Single to Chorleywood from a Flowbird* TVM and loaded it to my Key (the GTR-issue ITSO smartcard).** Upon confirming it loaded properly I attempted to tap in and was greeted with error code 57 (location not covered by pre-paid ticket) so Chiltern staff let me in after verifying the contents for themselves. I successfully tapped out at Chorleywood.

Above is a screenshot of my ITSO tickets on the Ecebs app. For some reason a long-expired single from High Wycombe to Aylesbury Vale Parkway (also purchased from a Flowbird TVM at the former) was not overwritten by my Aylesbury purchase; this contrasts with my occasional use of GTR's S&B TVMs (note the first so-called Period Pass listed is actually a Day Travelcard). Don't know if it matters but the Wycombe single was Network Railcard-discounted and the Aylesbury single wasn't.

My second Period Pass listed is a keyGo travel authority. As shown in the above screenshot I was landed with an incomplete journey and for some reason the system won't process my attempts to add the Aylesbury tap in, so I called GTR and hopefully the record will be adjusted by tomorrow.
When I used my Wycombe single last March the presence of keyGo plus an expired (and now overwritten) GTR-issue Day Travelcard from Luton was no problem, so my guess is the Aylesbury gates erroneously tried to validate my Wycombe single.
[* IMO the generic label "Arrive" can get in the bin]
[** I knew paper tickets / contactless were available but wanted an ITSO ticket on this particular occasion]

Above is a screenshot of my ITSO tickets on the Ecebs app. For some reason a long-expired single from High Wycombe to Aylesbury Vale Parkway (also purchased from a Flowbird TVM at the former) was not overwritten by my Aylesbury purchase; this contrasts with my occasional use of GTR's S&B TVMs (note the first so-called Period Pass listed is actually a Day Travelcard). Don't know if it matters but the Wycombe single was Network Railcard-discounted and the Aylesbury single wasn't.

My second Period Pass listed is a keyGo travel authority. As shown in the above screenshot I was landed with an incomplete journey and for some reason the system won't process my attempts to add the Aylesbury tap in, so I called GTR and hopefully the record will be adjusted by tomorrow.
When I used my Wycombe single last March the presence of keyGo plus an expired (and now overwritten) GTR-issue Day Travelcard from Luton was no problem, so my guess is the Aylesbury gates erroneously tried to validate my Wycombe single.
[* IMO the generic label "Arrive" can get in the bin]
[** I knew paper tickets / contactless were available but wanted an ITSO ticket on this particular occasion]