The T: drive in above original post is Samba file sharing on a Raspberry Pi. I also tested with a network share on my QNAP NAS and have same problem.
Saving a service scheme to a network drive makes a corrupt file
Ok, thanks for clarification. But it wish OpenLp had support for a virtual second monitor. Long video cables between computer and projector are more expensive than a network cable.
Problem to use JPLink connected projector as presentation screen