Hello big fellas... 
After trying over a hundred versions of gcam (5.3, 6.1, 6.2, 6.3, 7.0, 7.1, 7.2 and 7.3), i saw that the best version for it is 5.1 ... link below (MGC_5.1.018_MI8_V1b.pk)
https://f.celsoazevedo.com/file/gcamera/MGC_5.1.018_MI8_V1b.apk
This version works with all modes present in version 5.1, including portrait mode with hdr +.
I leave my settings in "FIX" all disabled (this is how hdr + works in portrait mode) and in saturation I leave it in "1.3).
After updating the settings, "Forced closed" the app and sign in again.
Any doubts ask me.

After trying over a hundred versions of gcam (5.3, 6.1, 6.2, 6.3, 7.0, 7.1, 7.2 and 7.3), i saw that the best version for it is 5.1 ... link below (MGC_5.1.018_MI8_V1b.pk)
https://f.celsoazevedo.com/file/gcamera/MGC_5.1.018_MI8_V1b.apk
This version works with all modes present in version 5.1, including portrait mode with hdr +.
I leave my settings in "FIX" all disabled (this is how hdr + works in portrait mode) and in saturation I leave it in "1.3).
After updating the settings, "Forced closed" the app and sign in again.
Any doubts ask me.