I get notified for an @mention but it doesn't appear on the mentions tab.
It's not very clear in the picture, but it states today's date being the 10th and the last update for a mention was the 8th. I had a mention on the 9th as well, which also didn't appear. that was ignored cause I thought it might have been a little glitch..
It started round about the same time started being active on invisible mode. Do you think it could be related?
I don't think it matters what mode your in. This is a bug that has been going on for a long time. Some have issues with it, some don't. For some it happens often, some it rarely happens. We have been award of it since it started but we aren't sure what is causing it (as far as I know). Dai is away right now for a little while so we'd probably have to wait till he comes back to take a look at it anyway.
I have had this happen a couple times, in both invisible and visible mode.