This is beyond annoying. At first I couldn't believe the small usb-c - micro-usb adapters just won't work even if they work well for charging and even data transfer. I did have two USB-C to USB-A adapters that work well with USB sticks and such but even if I have full boxes with all kinds of cables and adapters I don't have anything I can stick the Flir into (need micro-usb female).
Anyway I went on ebay and bought the first usb-c to micro-usb adapters (3 for 1 eur) that mentioned OTG and guess what - as luck has it the first from the 3 didn't work! I didn't even bother to check them all until today when low and behold ... two are working. So two are working OTG as (somehow) expected - FLIR and other adapters are working (like microusb to USB-A or whatever else I've had before) and one will charge the phone albeit slowly (transfer doesn't work too so probably something is wired wrong). The OTG adapters won't work for charging (probably expected).