Hi @Arnaud_Moncel @anon34731316
Looks like the solution is to use the carrierwave-base64 gem [1] in order to upload files via a smart action.
Now I am able to upload files via the add/edit user and also a smart action.
[1] GitHub - y9v/carrierwave-base64: Upload files encoded as base64 strings directly to carrierwave
Thanks again!