Yes, I've encountered this issue for some time now (SW 2010 SP 2 & 3.1) but haven't gotten around to posting it up or contacting my VAR.
Our symptoms appear to be different from yours but perhaps it is something similar. At least for us, whenever we define bolt connections within an assembly, the bolt connector "circular edges" re-arrange themselves automatically under the following conditions:
A) Right-click -> Open a part/sub-assembly contained within the feature tree
B) File -> Open a part/sub-assembly that is referenced within the original assembly
As long as you do not save the original assembly when the "circular edges" re-arrange themselves, re-opening the assembly will restore the bolt connections. The work-around we are using is to close the original assembly prior to opening a referenced part/sub-assembly. To say the least, this is quite the inconvenience.
Are any changes being made to any other parts when you experience this issue?
Could very well be. The assembly was set up for a failure test on the tubular part to which the bolts were connected, so in the course of setting up studies with differing wall thickness and hole counts etc, I opened the tube wall part and edited it numerous times (while the assembly was open). Of course, since I'd been experiencing some crashes during analysis, I now make a point to save pretty much every time I make a change to anything, to save having to redo it several times.
Our VAR provided a workaround, which is opening the part whose faces are changing (in this case the tube wall), hitting Ctrl-Q (to rebuild, I think), then save and close. The assembly should then update back to the correct bolt faces. This doesn't permanently fix the problem however, so I'm still waiting for an actual solution or fix from SW on this, but at least I got the studies done.
I suspect the "correct" way to handle this would be to set up all the studies first, and then put all the bolt connectors in afterwards and not change the study/parts. However, defining bolt connectors is by far the most tedious thing I've done in SW (WHY CAN'T I USE PATTERNS FOR THIS, ARGH), so I went with copying studies in order to save several hours of setup time.
Thanks for your post, I'm glad I'm not the only one this has happened to!
The workaround your VAR suggested did not work for me; I tried this in the past and the re-arranged bolt connections remained. However, I did upload an Rx capture for my VAR to investigate.
You're right that, ideally, the bolt connector definitions would be assigned prior to running simulations. But this isn't realistic since changes to the model are sometimes based on FEA results. I'm also copying the studies and drag-n-dropping elements in order to save time. Someone posted a way to assign bolt connections en masse when using hole patterns, so you might look into that since you're dealing with more bolt connections than us.
Any plans to upgrade to SP4? I'm tempted but will wait to see what my VAR suggests. G/L to us both!
Btw, have you experienced the same issue on newer parts?
I havent run into the same problem with a newer assembly yet.
Honestly, I haven't done anything further with it. I was able to run the studies after using the VAR-suggested workaround, and I haven't had any parts to make since. I'll let you know if I do, though.
I am in the habit of upgrading more or less automatically, whenever an update is available. Usually (with software in general) there are more fixes than new bugs.