The calendar I use on my btmail is broken to say the least. At present its display is all a looking a bit like its being updated and somebody didn't test it properly.
Mind you that's not all when the email itself times out instead of just going to BT.com again it seems to suggest I have done something wrong and does not know its come from btyahoo and I need to be Bt.com address. I thought the whole point of the recent change to bt/yahoo mail was that we should be using bt.com why not just force the reload instead of the redundant advice screen.
Sadly yet another mess ....☹️
Has your issue been solved? On another thread you were second to complain about this issue, (2 hours after the original thread post) but it now appears the first post has had his issue resolved, hence why that thread shows it as "Solved", even when many others have subsequently had similar or near-identical problems these past few days with the BT Yahoo Calendar interface.