1st layer problems with .1 layer height
You likely need to re-calibrate the Z-height of your nozzle. The reason that a lot less plastic is coming out of the nozzle at 0.1mm is that the actual gap is likely smaller than 0.1mm. This makes the print bed act essentially like a partial "lid" on the nozzle which occludes the outflow of molten plastic. 

Simplify3D has information on their website regarding the issue which can be found here: https://www.simplify3d.com/support/print-quality-troubleshooting/#not-extruding-at-start-of-print. Hope this helps!