I can confirm this one is happening for me too
DraconPern - I've tried with the latest ESR version (FMFirefoxCEESR-31.3.0-en-GB.msi) on Win 7SP1 x86 and x64. Integer settings (dword in the policy keys) are definitely not getting applied as locked settings unless the preference is set/created elsewhere (eg greprefs.js). Interestingly enough, if you intentionally set a preference with the wrong type and override it with a matching named GPO/ADMX entry, the preference is set as locked down even though the value is not updated/updateable to the value set in the GPO. That might also need a tweak but I'm not sure which setting should win (probably the GPO setting
[Edited to add something else]. I am slightly perturbed by the ADMX file storing "boolean" values as Dwords, is there some conversion going on or does FF understand 0/1 as true/false natively and not care?
[Edited after reading documentation]. Doh! ... ADM/ADMX files don't support REG_Binary or anything useful to discriminate between integer and boolean. I can see why booleans are stored as integers now