Photo Paint is deleting my images

Recently, i'm having an issue with Corel PHOTO-PAINT 2018. Every time I edit a photo it just disappears like black magic, VODOO or something...

This is the setup:

I have all images stored on a Qnap TS-431K.
My computer and the Qnap are connected on a network domain controlled by a Windows Server 2019 .
My computer access the images by a Mapped Disk.

This always worked fine!

Recently we upgrade de domain controller from windows server 2003 to Windows Server 2019. The DNS also have changed.

Since this upgrade i started to have this issue.
I still have a mapped disk (with new configuration now) and is working well and the permissions are ok (read/write).

I tried the same procedure (oped - edit - save) with other similiar programs(photoshop) and works fine.

Can someone help me on this. Its a server problem or a Photo Paint bad configuration?

Thanks in advance.