Hi all, I am setting up my DJI air unit/FPV goggle v2 on my Diatone Roma F5. The GPS coordinates on betaflight are correct. But strangely, on the Goggle, the GPS latitude is correct (same as in BF) but the longtitude is way off (an non-existent value)... Not sure what cause the discrepancy. Please help!! Thank you very much!!

Thank you for your question.  I have the same problem.  
I know about the missing zero next to the decimal place.  Your screen shows what should be 311.069663  (the zero is replaced by a space)
If I may be so bold our shared problem is  that there is no 311.069663  in the GPS coordinate system.
I have done some fiddling and find that to accurately convert the DJI latitude to a correct GPS format you have to add -429.5 to the number shown on the goggles.  (The resulting GPS coordinate is in decimal degrees and not degrees, minutes, seconds)
But now the question is: where did that  -429.5 come from? Does it make any sense to you?
Some math geniuses will probably help us out here.  

Hi Dr B. My solution is the same as yours. The precise difference is 429.4968 in my case. So every time in the field when I need to calculate the precise GPS coordinates, I substract the displayed longitude by 429.4968 to get the true value. No idea why but this seems to be a reliable work around.

same here - my longitude should be -122, but it reads 306 in the goggles