What if you set your Elevation Mask Angle higher than typical 15 if down in a hole? I.e. 20+
Try adjusting higher SNR?
Toggle QZSS off to see if that helps since that constellation isn’t too ideal from your region?
Incorrect RTCM3 message settings?
Screen shot settings in case to return to those settings and/or to compare.
Photos of surroundings from that point etc?
What material are they mining? Are you directly adjacent to a large stockpile?