Printing 0.1 when set to 0.05l?  

Different settings for first and subsequent layers

Most first layer defaults are .2mm - there is a separate setting for first and other layers in the layers and perimeters section.  0.4 nozzle is going to be rough going at that tiny layer height - layer height should be a proportion of the nozzle hole size.  So a .6 nozzle would have trouble printing a .1mm layer height, and a .4mm nozzle has trouble printing at sub .1 layer heights.  But I suspect what you are getting is what you asked the slicer to do - it doesn't change your mind for you.  It just has settings you may not be aware of.

RE: Printing 0.1 when set to 0.05l?

I noticed the first layer almost always starting at 0.2mm. I figured it's to prevent hitting the bed with the nozzle on the first few layers.

I've been digging through super and prusa slicer for about six months now and I'm usually between 0.15 and 0.3mm in layer height depending on what I'm doing. I usually 3dp in pla+ but the cf cpe has been my first high ish temp material at 270. On my stock 0.4 nozzle I printed a few detailed parts at 0.05 in pla+ before with color changes and it came out almost polished smooth. I don't remember what the screen said when I printed that though so actual layer height might've been 0.1mm. I'll try another cube in my other cpe without the cf and see if I can print a 0.05mm cube this time. I don't really need anything in 0.05mm but it got to my ocd that it didn't actually print at 0.05mm the last time. First layer was 0. 2 and the rest were 0.1 up to the very last one.