I got the enemies stuck in a loop here:
Also in that level, it was really unclear why I can't go through the gate to the red node sometimes - I thought it was because I had the yellow key but not the white key, even though that didn't really make sense. The following level made me realise what was going on, but even that level doesn't introduce the mechanic well.
I found it unclear how finding keys works - eventually decided that they're hidden in specific nodes, and some nodes don't contain anything? It feels weird that some are empty - I was initially assuming they all contained part of a key, and I needed to search all nodes containing purple to get the purple key.
In this level above, I initially searched just one of the nodes in the upper area. It happened to be the one with the purple key, so I thought I might need to go down to the bottom area to do something to disable the sentries to go back to search the other two nodes in the upper area. I made it a lot more complicated for myself than I needed to, because I was assuming that to complete a level I needed to search all the nodes.
The level introducing stealth/one-use keys - it felt like I only needed to use these through poor planning rather than because they were vital to the level. That may not be true, but that's what it felt like - feels like it might be worth reworking this level to make it more obvious why they're crucial to the solution.