The "%5C" parts of the path are "encoding characters" which have replaced the actual character with it's hexadecimal equivalent. In this case, the "%5C" is replacing backslash characters '\' which means the path should be:
C:\Users\raymo\OneDrive\Documents\Visual Studio 2017\Projects\C#\Models\Models\obj\Debug\Models.dll
So start by looking at where the "bad" path is coming from, and when you are getting it: if necessary do a file search in Windows Explorer to find where that string is referenced (You may need to use "Advanced options...FileContents" to locate it.
Once you've found it, you can start looking at how an encoded path got in there ... but we can't help you do any of that - we have no access to your system.
As a final "Nuclear" option, create a brand new solution, add new projects, and add your files to that slowly until either the problem occurs, or you get a working complete solution.