Proxy files won't stay attached, re-attaching everyday!

Hi,

Here is my workflow.  All of my original 4K A7s II footage is on an external drive and sits in the same folder.  I've made Proxy files with Premiere and those files sit on another external drive in its own folder.  I attached the proxies using right-click then Proxy>Attach Proxies>then found the folder>hit search to confirm the files, then once found hit the OK button.  It takes a couple of minutes and then everything attaches and the footage plays smoothly.

At the end of the day I SAVE AS the project and re-name it to today's date as a back up.  No folders or drives change names or locations.

The next day, the Proxy files are not attached and I have to attach them everyday.  So my question is, every time I save the project and rename it to today's date, does it un-attach the proxy files?  Or am I missing something?

Thanks.