I'm going to check into this. I noticed if you are placing equipment, then some pipe runs, and then select maybe a valve to place on a line, the OSNAP settings reset. This may need to go to Autodesk Dev team to be fixed. I'll let you know what I find out.
Quick question, are you all running Windows 7? Other people in the office here running Windows 7 (including me) are having OSNAP issues.
I am also having this issue, everytime I go to draw a new line, move something, or just sit idle for a few seconds my osnap settings change and my polar tracking turns off. I know its as easy as pressing F10 and going into osnap and changing the settings, but having to do this constantly every few seconds seems a bit much. My option settings are set the way I want them, but somehow P&ID has a mind of its own.. I would love to finally get a solution to this!
Also, I am running windows 7.
This appears to be fixed in AutoCAD Plant 3D and AutoCAD P&ID 2012. The only running snap that becomes active when selecting a symbol from the tool palette is the "nearest" snap. This is by design and is intended for object placement on pipe runs in P&IDs and 3D piping.
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If you fix the nearest issue, then I will accept as a solution.
Its very annoying when trying to move/place something and nearest magically turns itself on!
Until then, this is unresolved.
Are you using AutoCAD P&ID 2012?
In 2012 and 2013 the OSNAP settings will temporarily change (nearest, node, intersection) when you select a symbol from the tool palette. Once you place the symbol the settings should go back to what it was set to originally.