"Jumping" png files and "invisible" masks in graphics

I'm using Premiere Pro CC 2017.1

When I place a PNG still over my video (for example, a watermark) and try to move it, the image "jumps" and won't stay in the position I put it in. I will be in one position when I drag/alter the position co-ordinates, then it "jumps" to another position on the screen.  What is going on?!

A second problem is if I have a text/graphics layer over a video sometimes (and I can't figure out how to replicate) as I move the image it "disappears" under an invisible mask.  I've checked and there is NO mask layer or any other layer except the text and the video. It's like I'm moving the image and it starts sliding under some layer that masks it.  I can slide it all the way under this layer (which seems to occur oddly at the halfway mark on the frame)...The only way I can solve this is just delete the text and start a new text layer.

I've used Premiere for a while but not had these problems until recent update - it's very frustrating!  Any ideas what is going on?