Hey! Here are some methods I've used in the past to fix this issue, or similar ones.
If you haven't already deleted your cache, this is the way to find it. Go from there to your user, find and delete the mageps folder.
It will redownload the next time you open Mage.
If the issue persists, you may want to write a small execution to allow java to run when Mage loads.
Step 1. Put the MagePS .jar file into a folder on your desktop. The folder's name does not matter and can be whatever you want it to be. Just keep the .jar file the same, "MagePsLoader".
Step 2. Create a "New Text Document" in the same folder. In the text pad, copy and paste this command: java -jar MagePsLoader.jar
Click Save As, name the file RUN and make the text document not as a .txt but as a .bat. This can be done by changing this to this
By this point you should have 2 icons in the folder you created. 1 being the MagePs .jar and the other being RUN.bat
Everytime you want to open MagePs you will have to double click the RUN.bat to open the game. A command prompt will come up (please don't close that window it must be open to run the .jar)
I really hope this works for you! If you have any questions please reply to this.
Much love, Calzone