Batch Rename Deselects Files and Changes File Type

When I select an entire folder of files and batch rename, the status bar that loads only gets part way before it goes away and somehow deselects a portion of the batch so those files are not renamed. It's also, in some instances, changing the file extension -- mostly from jpg to mov or sometimes jpeg. This file extension issues happens mostly with iphone jpgs (not HEIC). The arbitrary deselection of batch rename files happens with all file types. 

Batch rename and metadata is a common daily thing I do and this has never happened before. 

I have updated my software and restarted multiple times yet the problem persists.