I think the issue maybe is that you are use Program "GTR (GTS, T-Rex) to GTR2 (GTS 2, T-Rex Pro) converter"
or "GTR (GTS, T-Rex) to GTR2 (GTS 2, T-Rex Pro) Converter & Editor" to convert from original watchface.
This program can convert but some elements will not work after conversion.
According to SashaCX75 , notified in the topic :
viewtopic.php?p=8844#p8844
If you would like to make a watch face for the T-Rex Pro to work properly. I recommend you to try "AmazFit WatchFace editor 2 for Windows" to create T-RexPro.
Because if use :
GTR (GTS, T-Rex) to GTR2 (GTS 2, T-Rex Pro) converter
GTR (GTS, T-Rex) to GTR2 (GTS 2, T-Rex Pro) Converter & Editor
Some elements of the watchface maybe will not work.
An example of a watch face created from the "WatchFace editor 2 for Windows "

Mod_tripledots_blue_ger_T-REXPRO_REAL_fORMAT.bin
I do not test on the real device , only test on Program editor , Because I do not have T-rex Pro