Living Sand Bind/Raise Spectre Not Working

I used a Bind Spectre gem to raise a Living Sand enemy in Keth. I equipped the Raise Spectre gem and ticked up the number to 1. No spectre appears. I tick the number back down to 0 and the spectre appears for a moment before vanishing.

The same happens if I increase the numbers and then decrease them. They only appear briefly when taking them away, but they don't seem to be present or active when their numbers are positive (ie I have 1 or more summoned).

So the skill gem I just used up seems to have been for nothing and has given me a useless non-functional minion.

Now I'm concerned that this may happen with other spectres if I try to raise any.