No, you said "I cannot use the official one for technical reasons". That could mean "It doesn't work on the pages I want to visit".
Given that Chrome itself loses and regains AS support on practically alternate builds, and other Chromium-based browsers vary wildly in their AS implementations (see eg here) there's a good chance that a custom Chromium build does differ!
How custom is this custom Chromium build? Can you point any of us to a download that we can test on a known working-with-Chrome system, given that you aren't able to?