My normal mic (1/4" mono plug) works fine when plugged into my Scarlett breakout box.  I use it several times a week, with no problems.
 
However, I have a few 1/8" headsets that I am testing, and cannot get any of them to work with the Scarlett.  Since they have 1/8" plugs I have tried different 1/8" to 1/4" adapters (some mono and some stereo, which I can tell by the rings on the male part) but for some reason I can never get a signal to the Scarlett when the source is a headset.
 
This is strange, since the headsets work fine on laptops which use 1/8" inputs.  And the mic which works fine with the Scarlett is not powered, so why does it work but the headsets don't?
 
Has anyone had problems like this? 
 
What are some things i can try to get the headsets to work with the Scarlett?

I'm guessing the contacts of the adapter are not fitting properly over the headphones plug.

Push harder? It is a bit hard to say.

I suspect the adapter.  Many headsets or headset/mic combos made for cell phones are TRRS.  I don't know which connections are for the mic and which ones are for the headset, but the correct adapter needs to be used.  Headphone jacks, on most, are stereo so you need a TRS plug. 

Could electronics contact cleaner help? I've never tried it personally but I've always wondered if it's a good first thing to try.

My guess would be you would need a splitter to split the stereo headphone signal and the mic signal.

If you record by speaking into the earphone does it work? (Not joking)

When "i" staff has started to rule headset market (4 contact connectors), I was waiting for the splitter to appear... But they was not available (the same connector was used in some video cameras before, but without the need need to split).
PRC was not fast delivering them, but after a while they have filled that hall. So get something like:
https://www.amazon.com/Headphones-Convertors-Headphone-Microphone-Simultaneously/dp/B01M8G1U0C
 

I just happened to wander in here today.  You've been overtaken by the lack of standards for headphone pinouts.  This article will help: [ http://www.circuitbasics.com/how-to-hack-a-headphone-jack/ ]