Ignored anchors in Thai Script

Some diacritics behave correctly in Thai, but others still don’t, and I’m not sure how to approach it. It almost feels like a bug. In the screenshots I included, you can see how I set the anchors on the diacritics and the result I get in Illustrator. Even when I move the anchors to test the positioning, Illustrator doesn’t show any change. As a note, the ccmp feature is set automatically.

I’d really appreciate help from anyone with Thai experience. Thanks.

Could you send me the .glyphs file and the string that shows the problem?