Ok so I got watch update (GVK7) and this is where I noticed the issue of ECG not recording and screen gets locked...
This is a bug
from Samsung, as you know with every update, new bugs are released lol...
Original Stock also has the same issue, not just the mod... I suggest you raise it to Samsung so Samsung can put some logic into shm, but till they release an official fix, I will be working on doing quick patch and prevent lockscreen from being triggered when recording ECG...
This is the broken condition:
For some reason while ECG is being recorded, the watch fails to detect it's being worn and ends up locking itself and suspending the ECG record (there is a 50% chance your ECG will be saved in the phone app and 50% ECG is dropped, never saved)
So yeah, if you have that issue, please report it to Samsung, and intentions meantime, I will try to think of some solution that works (may not cover all scenarios but will allow ECG to go through and save on the phone)...