In order to fix this issue, you have to apply the below given fixes one by one.
First fix is related to the compatibility tab. To follow this method you have to apply the below given steps one by one:
Step 1: You have to navigate to the C:\Program Files (x86)\Steam\steamapps\common\rocketleague\Binaries\Win32\
Step 2: Right-click on the RocketLeague.exe file
Step 3: Click on the compatibility tab and check the "Run as administrator" box
Step 4: Now, click on the Apply or OK
Step 5: Run the game again
Note: in case you play gems on several computers and want to keep your saved game then you have to do the same thing with Steam.exe because Steam is not able to read/write the data from the cloud.
Verify the Game integrity
To verify the game integrity, first you have to run the stem with admin privilege. Right click on the steam icon and choose run as Administrator
After launching the game now, go to your Steam games library and then again right click on the faulty game (the game suffering from the data saving issue)
Now, select properties and select local files
Again choose verify Integrity of game cache
This process takes a few minutes to do.
Source: How to Run Steam Games on Windows 10 without any Issues