Glad to hear it! My guess is that something went wrong when the previous project was imported, and an asset was incorrectly reported as a JPEG sequence instead of a static image file. It’s possible that AE then cached that asset state, so every time the file was loaded, AE saw it as a sequence regardless of whether it was previously removed or not.
We haven’t seen that particular scenario before, but it’s good to hear that you were able to get it resolved. If you run into any additional problems, please feel free to get in touch.