Mac with No check-ins

[PPAict]

Hello everyone!
Has anyone ever had a Mac not automatically check-in (and therefore also inventory updates) but only when the user carries out some operation via self-service?
It appears as if the incoming connection from Jamf is blocked/filtered, but is only available for outgoing.
It happens to me on 3 colleagues, on one I identified the problem, the OnVue software for online certifications, but for the other 2 I can't understand what type of troubleshooting I could do. Tried redeploying the jamf binary, no luck.
Has anything like this or something similar ever happened to you?

[AJPinto]

Check-in and Update in the inventory record mean different things. One is the Jamf binary and the other is the Apple MDM framework. If you suspect network shenanigans download and install the Jamf Environment Test tool, and run it. This tool will tell you what is blocked that needs to be open. You can also run the Mac Evaluation Utility which will perform a similar function, but doesn’t to check Jamf stuff specifically. 

Aside of that, make sure the devices are rebooting regularly. Both the Jamf binary, and MDM framework run on daemons which are just processes that can hang which stops devices from reporting back unless forced to do so locally.

[PPAict]

Thank you @AJPinto , i will try the utilities you suggested!