Problem with coordinates and job size

Hi I’m a new user of lightburn so this could be a user error. I am using a Ortur LM2 pro with a working size of 400x400 and using version 9.24 software on a windows 10 comp. my issue is that if I draw a box of say 400x400 and position coordinates of centre being xpos 200 ypos 200 and the box is definitely 400x400 if I save that file or change screens and come back the file would have re sized and changed coordinates by about .002 mm ,which means it will go out of the working area and not engrave. The machine settings are set to 400x400 and I can run the file if I change the coordinates and resize again , but this is happening on every job. I can write some text and set the height to 20mm but if I enter another line of text and set that to 20mm, when i go back to the first piece of text it will resize down to something like 18.98mm. This occurs if the work is on the same layer or a different layer .