I've been searching for an answer to this problem but haven't seen one. Some background information: Using SW Premium 2018 SP3 with Solidworks PDM 2018.
The problem I had yesterday at work. I have a top level assembly with two configurations, these configurations have a few levels of sub-assemblies and components all with a couple configurations. Everything worked fine the first day I assembled everything. All configs were selected appropriately and working well. The next time I opened the Top-level assembly everything went haywire. Nearly all my components had switched their configuration (or so it seemed), I started digging down into sub-assemblies, everything looked fine until I got to the individual component level and opened the equations tab where I found that my one extremely simple equation was showing the incorrect value (see attached picture). I do have the "this configuration only" selection applied appropriately. Note that it was working as intended just a couple days ago. The fix? All I had to do was check out each part, open them, open the equations dialogue box, hit OK, and everything went back to normal.
Any clues as to why this happened? This is a simple configuration and variable. Even though it was a relatively easy fix, I can't take time to do that if this is going to happen a lot.
Unconfirmed, but it appears to have happened only to parts where the equation driven dimension is on a feature (boss extrude) rather than in a sketch.
Thanks for any input.