Hi. I am on my 2nd transmitter in less than 100 days . They have been great at talking me through all ways to check that your phone is set up correctly and then sending me a replacement. It is frustrating not to have my 5 minute readings and it is much less reliable that the fsl which only has to talk to my phone and not my pump and phone!
My usual fix for signal loss message is to turn blue tooth off and on again then re install the app if that doesn't work.
Good luck and I hope you have an fsl or test strips as a back up... (I still have fsl on prescription so have a spare box on standby).