There is probably a bug linked to the usage with another plugin. If Media File Renamer breaks anything, please contact me and let's track down the problem. I had no issues on my side (with more than 4 websites which I am running) + there are many very happy users, but I know a few had issues. I really need to track them down so no need to come here to yell that the plugin deletes everything, let a bad rating and never help to find the issues. This plugin is a lot of work and doesn't deserve insults. Thanks, I really appreciate your understanding.
SOMETHING IMPORTANT TO REMEMBER: In the description of the plugin, it is written to first try to rename a few images one by one before using the bulk functions. Please do so, make sure it works for you. Then backup your files and databases.