Bug has been reported to Mozilla here and is a work around

https://bugzilla.mozilla.org/show_bug.cgi?id=702280

Global Extensions are installed here /Library/Application
Support/Mozilla/Extensions/{ec8030f7-c20a-464f-9b0e-13a3a9e97384}/

I created my override called GlobalExtensions.js here
/Applications/Firefox.app/Contents/MacOS/defaults/pref/

Contents

pref("extensions.autoDisableScopes", 0);

Done Global extensions working again :)

Tim Kimpton
Systems Engineer
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