Do you also have issues with the Casio Auto Time Adjust function via Bluetooth? I own a Casio GMW-B5000 and I wondered why sometimes it did work and sometimes it didn’t. After lots of testing I finally found the issue and rest assured, probably it’s not your Casio watch, good chance it’s your phone!
Modern phones are using all kinds of energy savings tricks and one of those is battery optimization. But…it isn’t enough to switch off battery optimization for the Casio G-Shock app. The Casio app is just working fine but it’s the Bluetooth adapter that is failing after the system puts it to sleep to save energy.
So what I did is write a small script using Tasker which toggles the Bluetooth adapter one minute before the Casio watch tries to connect to the phone to automatically adjust time. Why no toggle? Because switching it off and on does not remember the previous state. It might be that Bluetooth was switched off for a reasons and we want to keep it that way.