Problem getting When Last sync with Dropbox

[Jedi]

I recently get a Samsung Galaxy Tab Active2 with Android 9 system.
I install When Last (v2.21) app from Google Play Store, delete all visible (default) items then set to sync with Dropbox, authorize with Dropbox (app version 170.2.8, installed from Google Play Store) with Dropbox Plus (paid) account. But it does not sync yet.
Status report: Waiting for initial Dropbox sync to complete. I know it takes a while, but it takes already 3 full days.
It's been years since last time I set up When Last sync with Dropbox (on another ancient Android tablet). I don't remember how long it shall need to initial Dropbox sync.
Please help!

[mouser]

Dropbox canceled their sync api, so WhenLast sync no longer works.. 
I've got plans for a replacement sync function, but it will be a while..
You can still manually export a file from WhenLast on one device and import it on another, for a one time thing..

[Jedi]

Hummm, WhenLast (on new device) crashes while importing file, exporting file, or sync with Public folder.
I already granted WhenLast the permission to use storage.

[mouser]

Yikes, ok let me test.

[Jedi]

I find out an workaround to this issue.

If I delete all visible items first (so that there is no item at all) then any import/sync operation crashes.
But if I add any random item first (so that it is not empty) then import/sync operation works.

BTW, how about make a Google Drive sync? Since it runs on Android system.