Big overlooked piece of maintenance when it comes to skimmers is air gets pulled into the venturi. Since by definition there will be air going through there pretty much constantly it's quite easy for "salt creep" to start to plug up your venturi hose and make it "not working"
Are you dosing before your skimmer chamber in the sump?
When I ran my current skimmer in DFW I never cleaned the pump. Here it went maybe two months after I changed my dosing to clog. I’ll be changing my dosing location accordingly.
Maintenance should not be overlooked, but neither should system design (says the guy with a chromis that just jumped his overflow).
Not unless it's humidity from the tank, and the sump was in an open area. Dry air in the winter, and dry air due to strong A/C in the summer. When I messed up my dosing here it caused a precipitation issue that got my circulation pumps at the same time as the skimmer. Fixed that and all has been well since.
For whatever reason I haven't had issues where the air line comes in, just between the magnet and housing.
Thinking about it, I should look at my spare skimmer that was having starting issues and see if it is scaled up.