Asklemmy

That sounds similar to the issue I ran into, Syncthing will create a .st-ignore text file (can't remember the actual name) that links the device folders together. When I've deleted that I've encountered similar confusion and problems trying to get new folders running.

If you have Android clients, I've found Syncthing-Fork to be slightly better for the initial setup.

What I'll tend to do when I have problems is remove each folder I've set up in Syncthing from both devices, then I'll usually create a new folder path for my purposes. If I've already set up when I'm trying to accomplish then I will either rename it (sometimes it helps) or just try from the beginning again.

For example, I want my tablet to get videos from my phone and my PC, and I want these files backed up in general. So on my phone I create /Send-to-PC and on my tablet I create /Receive-from-PC. Either the host or the client can initiate the synced connection for the first time setup, so it's just a matter of naming the Syncthing Label (such as a comment descriptor about the folder, like Media), setting the folder path within the client device (on android this might be /storage/SD-Card-ID/MediaFolder) and then choosing which devices will be connected to this label (usually via a tick-box with the Host or Client name). This is usually it, but you do have the option to set Folder Type for whether you only want to send, only receive, or send and receive, as well as Watch for Changes.

These last two may also be part of what you are noticing too. For example, if you have Watch for Changes disables, you'd have to wait for the scheduled upload, which can save phone battery by not having it sync constantly, but can also prevent syncing quickly when you want it. Or, more likely what you may run into, Send & Receive being the default can result in some odd quirks when you the Host removes an uploaded file to the client. All of the sudden your project file is vanished! This happens to me from time to time, as I'll upload a video I want to edit on my tablet, then I'll move/delete it since I'm in the process of editing, only to remember that Send & Receive makes it so that the client also moves it from the shared folder.

Anyway this probably isn't very helpful, but hopefully seeing a tired rundown of how someone else uses it gives you an idea of what may be happening on your end!