User can create file in share, but not copy/write file to share

I have just built-up my second ever Freenas server. This one is running 11.2-U6. I've created a pool, datasets and samba shares (all of my users run Windows 10). When I browse \\Jessie\ in Windows File Explorer, it sees all the shares that I created. If I right-click in any of the shares, Windows will allow me to create a new file and save it there (right-click, New, Text file). However, if I try to copy a file to that share, the operation fails. Clearly I have setup my ACL permissions...

User can create file in share, but not copy/write file to share