I'm not sure if this is a bug, and it's been a long time since I've played, but I thought GM meditation meant a 100% chance to actively meditate? This is not the case on this shard.
If your mana is very low you may fail at GM. Also anything above leather armour (barbed/horned/magic is fine) will slow down mana regen with and without med.
Mana wasn't "very low", around 50%, and wearing leather armour only. My memory of how this worked in the olden days was that it was 100% successful. The only factor I can think of that might have made a difference was perhaps not being well-fed. Does food make a difference here?
If it was a "1 off" situation then I wouldn't even worry about it. As AlexCCCP had mentioned, very low, basically red lined, or heavier armor normally are the only times that make you fail. Id definitely take note if you see a trend of fails when it's not suppose to though.
If that had been the case, I agree, I would not worry. I took screenshots (I was raising magery and EI at the time) and checked the time signatures and they were 6 minutes apart, but in terms of using the skill, they were twice in a row. I have 21 AR on this character from basic magical leather. Wearing sandals, not boots of any sort. As you can see from the screenshots, I was at 70/110 mana (blessed) and 47/100 (unblessed). Now take into account the time I tried to meditate and took the screenshots, those values would be lower, but are far from red-lined. From my experience years ago, this should not happen.
And this shows my AR and armour worn (that I currently wear and was wearing during skilling up today). It also shows where my boat is, north(to the right) of the pirates in Occlo, so come along and gain some skill if you wish to. I set it up daily after sailors despawn
On an entirely unrelated note: You should use the new razor. http://www.uor-razor.com/ (Sorry I swear I'm not stalking you. )
I use the Razor from the download package for the server, but have been thinking the same after seeing mentions of scripts requiring a later version than I have. Will probably do so tomorrow, as I am drinking tonight and have at least a -20 int penalty lol