Can't copy file larger than 1M from Ubuntu 18.04 to windows shares - Invalid argument

I can't copy any file larger than 1M (don't have issue with smaller files) from any of my Ubuntu 18.04 to any windows shares (on MS server 2018), got "There was an error copying the file into smb://.... Invalid argument"

Working fine with machines running 16.04 or mount from command line (mount -t cifs....)

Really appreciate any pointers on how to fix this.

Thanks,