How strange... yeah the original problem was likely related to exectuion order, but it looks like everything's working now? Actually, the issue might have been that I was using a material called UIMasked, and I can't remember if I made that myself or if it came with an older version of STM. Either way, I'm currently using the UIDefault material (because masking is built-in now) and it appears to be working. Could have been some obscure material setting messing things up.