Hi @andargodk
A warm welcome to the ODK community and forums, please when you get a chance, introuce yourself and we would encourage you to use your picture an avatar it helps build community.
It sounds like you are using Ona as your server, you will get better support from the Ona team.
Make sure that your form uses the .xlsx format if you coding your forms using XLS Forms (Excel) or convert to .xml
.xls support was dropped, for background you go through this forum thread