It does not appear to have scripts attached to make its AI function.

I'll back this up to some extent.

From my own experience of using of the Ooze Summon Stone with the Summon Creature 1 (2) and from seeing others use it, the summon will not be able to move from the spot it was summoned at. This has happened several times at different places, so it's not got to with the summon being blocked to my knowledge.

It was working just fine before, but for some time now they just stand at the spot.

Its the scripts attached to the summons, or rather, the lack of one or more.

I've had this happen to summons on other modules and systems I've made.

No, actually, it's a balance fix. They deliberately are unable to move, although are able to fight fine if something comes up to them.

The ooze summons are already far more powerful than pretty much every other theme, and for them to have True Seeing on top of it made us decide that the smallest ones needed something to balance them out a bit.

IC'ly they are just a very small ooze blob that hasn't mastered movement yet.

No bug!