Hi,
This issue have been there for quite long time since I purchased Fenix 3 HR. As the topic title, the available slots in Connect IQ Android is not updated correctly when uninstall Apps/Widget/Watch Face/Data Field most of the time.
I have utilize all 16 slots all the while and when I found new Apps/Widget/Watch Face/Data Field at store which I want to try out. I will uninstall from Connect IQ Android. After uninstall, I checked from Connect IQ > Manage Storage. It still showing 0 in Available Slots.
I have to power off Fenix 3 HR then on back only the available storage updated correctly.
This post hopefully can open the issue to Garmin team to investigate it because it is happen very long time already.
Fenix 3 HR (Firmware) : 4.90
Connect IQ Android : 4.15.1