Here are some files made in simulator mode, I will upload files from an actual field later.
SurveyAutoSave.txt (12,6 Ko)
Survey_2021_Aug_29 19_00_38.ags.txt (8,8 Ko)
For open in design software you must use the ags file but you can modify the extension to .txt.
The easting/northing in surveyautosave.txt have only meaning/value in opengrade in this specific field.
here is an .agd made by Optisurface that works on OG3D:
ch65_1.agd.txt (125,9 Ko)
EDIT: Seam that 125ko is to big?
ch65.zip.txt (62,5 Ko)
Maybe you have to modify a little the save/open code to make it work.
Or upload a file here.
Right now OG3D read only a few zone(subzone) coordinate, you have to give specific names, look at the Github readme.