i did have this once many years ago - for some reason DUB fed back to BA that I was a no-show for my DUB-LHR flight which was the first one in the booking heading to the US. By next day all the other flights were cancelled. This was sorted after a call and a wait of 1/2 hours whilst they went off and checked the manifest, then reinstated the flights.

It has nothing to do with you not going via flight connections.

It can happen, but it is very very rare, so I can't see there is anything you need to do or worry about for the rest of your booking.

How long ago was this? I would wait for a week or so to see if your JER-LHR and LHR-OTP post. If not, then do a claim for missing points to BA.