Cannot open file from the menu

[opk12]

Click the three dots menu. click any of the Open (:new/:vnew/:tabnew). The system file selector is opened. Select a file, read the error E303: Unable to open swap file for "/document/primary/gpg.txt", recovery impossible. A new empty buffer is opened that refers to that path. The same file opens fine with Ghost Commander's Open with... menu item. Android 7, VimTouch 2.3 from f-droid.