Can’t build reopened saved files on sublime

Question

So I’m learning Python, Tkinter specifically, and I’m coping a video. It works perfectly fine the whole session, but every time I close the file and reopen it later it won’t actually build and it shows me random syntax errors on the same lines of code that were just working. If I copy and paste the code section by section on to another file it works again. But if I copy and paste the whole file it will give me random syntax errors. I’ve been looking at the build system and file path and they’re all the same on the working files and non working files. The code is exactly the same and so is the build system, if anyone could help me I’d really appreciate it!