I have been having issues with Finder and the Dock ever since the upgrade to 10.10.1 (I can't be certain they weren't there in 10.10).
I am unable to drag items off of the Dock (to remove them). I also can't drag items from the download stack that I have beside my trash can in the dock. Dragging the item simply does nothing. If I drag it somewhere and release the mouse button, it just opens the app/file.
And in Finder, I am only able to drag and move/copy 86 items. I can select more but when I drag them to a new folder or other location the most that will get moved is 86.
I have confirmed the issue with a friend but have several other friends for which everything is working fine.
I have a mid 2012 retina MBP and my friend has an older (2010 i think) non retina MBP. I have restarted several times and tried to find any sort of setting that might be turned off. Googling doesn't seem to turn up any information either. So I am mostly wondering if anyone else is having this issue and/or if it is an OSX bug or how to fix it.
Running repair disk permissions from disk utility then restarting worked for a while. But then things went right back to not working again. Going to test some things to see what might be causing it to revert.
It turns out that restarting does fix it temporarily and repair permissions has nothing to do with it. I am assuming I didn't notice this before because it is being caused by an application that was reopening (because I usually check off the "Reopen applications" option).
For clarity, here are videos showing what the issue is.