Stuck on step zero

I’m working on wave equation simulations with an external source. It was going fairly well in (1+1) dimensions. But when I added another spatial dimension, moving to (2+1) dimensions, I got a weird problem.

My code runs without errors and I get the usual messages indicating that my training is starting. But it gets stuck at step 0 and doesn’t output anything into terminal after that. The last terminal output is “[18:42:18] - [step: 0] record constraint batch time: 1.257e-01s”.

I don’t know what is wrong with my code. Does anyone have an idea?