It seems once I finally switched to nuclear power, that after I removed all Regolith furnaces that my miners stopped working, even though crystals are required to get Regolith through building mines constantly (which I hate doing).
I believe the bug is that you require a Regolith Furnace in order to harvest crystal, even though you have a Raw Materials Depot placed and have plenty of storage.
I'm on the web app, in Firefox. I can't find the version number in game anywhere, but its whatever the current active version is.
I suspect the bug is an oversight, in forgetting to enable miners to drop crystal off at other locations other than Regolith Furnaces.