SharePoint file is updated for me but not for others

Question

Hello,

When I make updates to a Project file on our company SharePoint server and save it, the changes apply in the file but the "Modified" date on SharePoint sometimes doesn't update. Also, I can open the file from SharePoint and see the changes, but my team is only able to access the older version. This issue affects two of four files in the folder. "Save As" doesn't change the Modified date, nor does refreshing the page. Downloading the file, working on it locally, then uploading it works for another team member (and has for years) but only sometimes works for me.

The two other files in the same folder update just fine, and the Modified date updates as well. If I make a copy of the file in question, it works for a certain amount of time (45 minutes? I left my computer, came back, and the changes weren't saving). However, I can't just copy the file as a workaround because I want to retain my version history. This issue affects other files and folders as well, but has mostly been tested in this one.

The first time I open the file, make a change, and try to save it, I get a popup error for a millisecond before it disappears: "Upload Failed - We're sorry this didn't work. Try saving again later and if that still doesn't work, click Save a Copy." I can't even click on the button because it disappears so quickly. I had to take a video and pause to read the error message. This error doesn't happen again until I fully close the Project window and reopen. Deleting my windows cache helped with these errors for about a day or so, but the file still doesn't save for other users.

I have tried resetting OneDrive, disabling/enabling Sync settings, restarting my computer, logging out and back in, and am unable to see anything regarding Files Needing Attention (many threads refer to this). The users in question all have permissions

The save and OneDrive settings for all these files are the same - why are my updates only visible to me, only sometimes having this issue, and why isn't this updating SharePoint for everyone?

Thanks,

C