No Error message, but user script had no change on 4chan

[mvineetmenon]

System Config:

FF 56.0 (64 bit)
Greasemonkey 4.1

The userscript is loaded, but 4chan theme is plain vanila. If I remember correctly, happened right after the most recent greasemonkey update on 13th December 2017.

[zertap]

Yeah me too.
Waterfox 55.2.2 (64-bit)
Greasemonkey 4.1

[Penwy]

had same problem,
Firefoox 58.0.2 (64-bit)
Greasemonkey 4.1
Resolved it by switching from greasemonkey to tampermonkey.