Inconsistent snap behavior

[dsummersPEG]

Why does Autocad behave inconsistently with regards to the snap feature? If I try to draw a line snapped from a starting point on an existing line, and move the cursor perpendicularly to another existing line, and I have the perpendicular snap on, why does it instead snap to midline instead of perpendicular, but sometimes it correctly snaps to the perpendicular? This seems to be based on which drawing I have open.  The behavior is inconsistent between files. I am using the same version (Autocad MEP 2024), same workspaces, same settings. I am opening the 2 files in the same instance of Autocad, but I get different behaviors. Without the correct behavior, it takes me 5 times the effort to simply draw a line where it's supposed to be. Just a line! I have attached screenshots showing the correct and incorrect behavior. NO, I WILL NOT POST MY DRAWING FILES.

[paullimapa]

If your DSETTINGS have both Midpoint & Perpendicular checked, then you may need to toggle (press TAB key) between them to get the osnap you want

https://help.autodesk.com/view/ACD/2024/ENU/?guid=GUID-76B81C1A-373E-4BCD-975A-789FB36C89FE

[Kent1Cooper]

When you have multiple Osnap modes running, if you don't cycle through the possibilities with TAB as @paullimapa suggested, it always snaps to the closest of the possible results to the cursor location.  It has always worked this way.  In your "wrong" image, all you need to do is move your cursor leftward enough that the PERpendicular location is closer to the cursor than the MIDpoint location is, and pick when the notification and green icon are about PERpendicular.

[TheCADnoob]

you can also look into temporary overrides

https://help.autodesk.com/view/ACD/2022/ENU/?guid=GUID-CF6E6F93-7D33-4D54-9167-2CC7473DA660