It seems like the game would go to a stand still after you unlock The Millionaire achievement in the game. It would just freeze and would not let you accept or do anything about it. There are users who complained about the game randomly freezing in the career mode too. Lets see how we can get this fixed.
Monster Energy Supercross 4: Game Freezing in Career Mode after The Millionaire Achievement | How to fix
For what it seems , there are may users saying that the graphics settings could be the issue. However it is not the case since people have tested it out on every graphic settings and the issue still occurred. There is no official fix for now. It could be a corrupted file which makes the game freeze. Users have tried deleting saved data and it still did not work. We may try this step and see if it works or not :
- Launch Steam
- From Library , select Monster Energy Supercross: The Official Videogame 4
- Right click on it and select Properties
- Then from the left hand side select Local Files
- Now click of Verifying Integrity of game files
This is should run a check on any corrupted or missing files in the game folder and re download the required ones. However if this doesn’t work for you then waiting for a patch fix would be the best thing as of now. You can try Re Installing the game too and see if it works for you.