I do actually have the same issue, the flic app with other actions work well, the unified remote itself too. Though the actions thru filc to unified remote are just not triggered.
My setup looks as follwos:

• OnePlus 3 Phone with Android 8.0.0
• Flic App on the Phone and one Flic Button connected
• Unified Remote App installed on the Phone and a Server Client on Windows

Does anyone have a workaround here?