Formatting lost upon saving

Didn’t clip and paste, was file-> placed..

Paragraph and character styles were clicked on and saved throughout the document

Saved constantly throughout the update process

Screen shows (for example bolds that were styled accordingly)

Document saved at 4:27

Next day opened the file and the styling was missing sporadically throughout document

Closed file

Restarted computer

Opened file again to double check

File is not correct, yet ALL words are there from save at 4:27.. but formatting is not!

Windows 10 PRO box networked to Windows Server 2012R2 InDesign version says "2015 release"

and as stated earlier.. all words are there, just NOT the formatting!

any ideas?