Luci-app-rtorrent keeps returning Form token mismatch

I’m using GL-AR750, test firmware 3.003, OpenWRT 18.06.1 and installed rtorrent rpc together with luci-app-rtorrent v0.1.5. After install and configuration I want to add a torrent for download, but the GUI keeps on returning:

Form token mismatch

The submitted security token is invalid or already expired!

In order to prevent unauthorized access to the system, your request has been blocked. Click “Continue »” below to return to the previous page.

I tried to remove Luci and reinstall (like mentioned here: AR300M 2.27 firmware issue - #6 by kyson-lok), but that doesnt do anything. The pages load, but when I want to submit something this error pops up.

Anybody any idea what I can do to get this working?

Thanks!

I would recommend that you use transmission btw, has more features than rtorrent.