Oookay, I’ve found the cause. Yes, I’m adding “walls” on the left and on the right from the game container:
And the bug appears depending on how these walls are set in the index.html:
<div id="wall"></div> - works
<div id="wall"/> - does not work
The curious part is - it was set as <div id="wall"/> in my templates from the beginning, but in old index.html I see it’s set as <div id="wall"></div>. So I guess, previously Defold was “fixing” these tags for me during index page generation and now something changed.