Could you please open project setting on GitHub, go to Webhooks, find AppVeyor webhook and check recent deliveries. For webhook related to the problem commit, check response from AppVeyor, If response was OK (204), send us GitHub delivery id for this webhook, commit ID, AppVeyor project name and exact time (in UTC or with time zone) when webhook was sent.
Oh, thanks a lot for update. I just started looking into it and indeed I see the following error
Error parsing appveyor.yml: (Line: 43, Col: 7, Idx: 1426) - (Line: 43, Col: 9, Idx: 1428): While scanning a block scalar, did not find expected comment or line break.
but also I see (maybe for different commit) that build is filtered out because you have branches/only/master but branch is Issue91-AppVeyorLinux. This is for commit badd972022828fff6cee7005146865efb5e96164.
Yeah, but it's kinda hard to find out the issue. I noticed the issue only when a try to create a pull request and the direct link to the CI Build was created by GitHub website. The history view is not showing this errors.