This was fixed for a while, but it seems to have resurfaced now. The bug where it's impossible to obtain a talisman with an "assign skills only to one lemming" requirement has resurfaced. Have not investigated whether the "Max one skill per lemming" ones have the same issue.
Also, any talisman that specifies a restriction to the number of Fencers that may be used, seems to be impossible to obtain if any Fencers are used, even if it's within the limit.
I have only confirmed these bugs on the V10.13.16 experimentals, and not on the stable version.
The one-skill-per-lemming thing appears to be a false alarm: The level I noticed this on also has fencers.
Fixed for next update. :)