Save/Edit Button Stopped Working On Block Edits

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Hello! I have a site I put together on Concrete 5.6.3.1, using a simple custom theme I made based off Skeleton. Everything worked fine but now the Save or Edit button in the Block Edit Mode box will not do anything. It seems to work using a default theme, but not with my custom one. It worked before, and now nothing.

It gave me no problems until recently, and I'm struggling to see what could have happened to cause this. I even tried a fresh install, then uploaded and installed my theme, and now it won't let me Add a block. Absolutely everything else works fine, except Save, Edit, Add and also the Upload button in the File Manager. I can use the multi-file uploader fine, but the single file Upload button doesn't work.

Everything was working previously, and everything in the Dashboard works fine, popups save properly, etc. I checked the console for errors on the button, but nothing really came up. One button had an error about the typography.css file being missing, but even by placing one in my theme dir it made no difference, still couldn't save content.