I can confirm that using a different structure to hold onto the ‘converted’ data from the initial structure appears to have eliminated the problem for me - I ran with the modified firmware last night for an 8 hour stretch with no order-of-magnitude latitude or longitude data values.
I will fork and post my changes to github so they can be pulled into the maintainer’s repo for something official.
In the meantime, here is my updated hexfile with the changes
xadow_phone_gps_v2.hex.zip (21.3 KB)