(https://i.postimg.cc/W4dkrxCS/bug-report.png)
This bug was encountered during roundthewheel's 35th anniversary birthday stream just now. He was using Super Lemmix on the stream for Timed Bombers.
Using the climber at the ringed point in the picture (which is Temple of Love from OhNo) will result in the Lemming bumping its head on the top border of the level and just fall back down. We had to ultimately skip the level because it couldn't be solved due to this.
Wicked 10 is still solvable even with this bug. I know, because I originally didn't solve the level the "intended" way all those years ago when I was a kid.
https://www.youtube.com/live/L9L3fBn5ilo?si=FH0vEMdKnxyfZx_d&t=6641 (https://www.youtube.com/live/L9L3fBn5ilo?si=FH0vEMdKnxyfZx_d&t=6641)
Dos Lemmings, but the solution should still work on both NL and SLX.
Anyway, this climber detecting the ceiling sooner than he should and falling back down rather than successfully climbing over also happens in SuperLemmini v.104a, and I agree that it's a bug when he's able to climb over fine on Dos and all the other original engines.
I remember telling Willlem about this. He said it wasn't a bug as I recall. I told him about a few levels I had to fix in Dovelems and Pimolems too for SLX as climbers did the same thing in those few levels of those packs. I think in previous versions of SLX the climber could get over, but in later versions, I think he changed it.
Anyways I just fixed the levels by just moving the levels down 2 pixels.
Here I did the same for Oh no more lemmings wicked 10 Temple of Love.