Haven't used my drone in a few months, and having some issues now that ive turned it back on.  Within the Go 4 app (ios on an iPhone 7+), the RC and HD signal strength icons are grey and / or showing no strength.  However, the drone flys and seems to transmit images just fine. I've re-installed the app and re-linking the RC several times. Not sure what to do to fix this.  

Hi, sir. What is the version of your app? I would recommend you upgrade your IOS system to 11.2 and reinstall the app. If the problem remains, please provide a screenshot about it.  

If your rc firmware is 1.9.2 and DJI GO 4 4.1.18, you can refer my post
https://forum.dji.com/forum.php? ... obile=2#pid1069840?