Excel changes the owner of file during save

When Excel saves my workbook file, it changes the NTFS ownership of the file to the user account that is using Excel. I need it to allow the data to be changed within the workbook, but not change the file's ownership. Any ideas?

• Windows 10 Pro ... clean recent install ... all updates are current
• Office 2010 (Excel) ... clean recent install ... all updates are current
• The original owner of Excel file is in the Administrator group
• Excel user is not in the Administrator group
• Excel user has the following inherited permissions to the file, through a group, inherited down from the folder in which it resides:

Modify
Read and execute
Read
Write

• Excel user does not have the following permissions. I checked this in Properties using the "Effective Access" feature:

Full Control
Change permissions
Take ownership

The only unusual thing is the Excel file came from an XP machine. I don't see how that would affect anything but ...

Any help with this would be greatly appreciated ... I tried everything I can think of, and have searched this forum and the internet without success.

Thanks
Skiff640

I just duplicated the problem with a brand new Excel file that had nothing to do with the old XP machine ...

• Signed in as the original owner who is in the administrator group
• Created a new Excel file in the same folder as above
• Edited the file with Excel as the original owner ... saved
• Checked ownership and permissions. Everything looks OK, including the inherited permissions from the folder
• Signed off
• Signed on as a second user who is not in the Administrator group
• Edited the the file with Excel as the second user ... saved the file with changes
• Signed off
• Signed on as the original owner
• Checked ownership and permissions. The ownership of the file has changed to the second user.

The original and second users are the exact same users described in the post above. Uggghhh ...

Clueless in Houston ...
Skiff640

I confirmed the problem again this morning, this time launching Excel directly from the Start menus and then opening the file (instead of double-clicking the file itself). Same thing as before ... the ownership of the file changed when Excel saved it.

Something is seriously broken here with security. I wish I knew how to get Microsoft to look at this ...

Skiff640