Solved! Error did exist with the sheet's HTML. Use unique html tag names or IDs people. ------------------------------------------------------------------------------------------ Experiencing a very peculiar bug in the Star Wars FFG Character Sheet with the critical injury effect radio selection box. I have been diving into this bug for a while now and as far as I have been able to conclude the bug is not being caused by the character sheet's HTML, CSS or JS. I am going to try and explain the issue as best as possible. When you click on a critical injury's effect radio button (Checked) Sometimes the radio button clears itself a few moments after you click it. (Unchecked) Unless you click a second time. The peculiar thing is that according to the chrome inspector the radio button still has the value of checked in the html though it's not checked visually In the css the :checked selector also isn't being respected and isn't evaluating to true so rules like .sheet-switch [type=radio]:checked .sheet-switch-input-off:checked ~ .sheet-switch-selection don't get attached. The console log shows an interesting story when you click the first time and you have the error happen. Here we can see the request sent and the responses from Roll20's app.js Now here is the interesting thing When you click the second time to "lock in" your choice the request doesn't fire again. The only addition to the log is the additional CLICKED statement. What it feels like to me is that Roll20 tries to execute the request, errors out and then tries to fallback resulting in the radio button being unchecked. It still doesn't explain the disconnect between the html checked value being set while the visual check is gone and the css :checked select fails to evaluate to true. By this point I would love some other eyes to look into this to see if there's something that's missing.