Pix4Dcapture is not displaying any information about the signal while flying. The behavior the drone should adapt in case of signal loss is defined in DJI GO 4 as it is shown in the screenshot you sent and this behavior can not be override by Pix4Dcapture.
Also Pix4Dcapture is only displaying the battery information of the drone. In your case it seems like a failure occurred which lead the drone to land immediately.
Could you reproduce what you experienced? In some cases, if it can’t be reproduced, it might comes the drone and we suggest to be sure on how to interrupt a mission if an unexpected behavior occurs.
I would suggest you go through the basic checks and troubleshooting steps as it will solve most of the issues that can be encountered by users if properly followed.
The Safe mode, using the iOS version of Pix4Dcapture is a specific mode to trigger images. It can lead to a RTH of the drone with its battery still being quite high due to a DJI limitation but it does not seem to be your case.