When I try to replace any blocks with beacons:
/fill 3 111 -118 -11 111 -118 minecraft:beacon 0 replace minecraft:glowstone
I get the error "Data tag parsing failed: Invalid tag encountered, expected '{' as first char."
The command works without the replace and when beacon is the block to be replaced:
/fill 3 111 -118 -11 111 -118 minecraft:beacon
/fill 3 111 -118 -11 111 -118 minecraft:glowstone 0 replace minecraft:beacon
I have screen shots if you require. If you need logs, I run the server local so if you need anything, let me know. I also have screen shots of all three commands if you want/need them.
Linked issues
Comments

Duplicate of MC-61864; beacons are tile entities.