Hi Icarus. I'm Greg, awarded MVP for eleven years, Volunteer Moderator, and Independent Advisor here to help you until this is resolved.
You don't need to redeem them, just buy them which it looks like hasn't gone through.
See here how to buy Robux:
https://www.wikihow.com/Buy-Robux
Go here to buy them:
https://www.roblox.com/upgrades/robux
If it's not working try again tomorrow in case it's a server issue.
If not then Make sure you are signed into the game and MS Store at top right corner Profile icon. This saves Store games progress.
Do you know when this started? If so See if you can System Restore to a point before the problem began following this guide:
https://www.windowscentral.com/how-use-system-r...
System Restore is your first line of defense and can take you back to a point before a problem began. If it doesn't help then you can undo it. Read about it first in the tutorial above and then try restoring to just before this started.
If the problem repeats or System Restore doesn't work then check which Windows Updates were installed at Settings > Update & Security > Windows Updates > Update History, uninstall them there or System Restore again, then immediately check for and block the Updates with the Hide Updates tool explained here:
https://www.howtogeek.com/223864/how-to-uninsta...
Even if you've already tried one of these steps, please do them over in sequence:
1) Check for game Updates in MS Store Hub (three dots at top right of Store app) > Downloads & Updates.
2) Run the MS Store apps troubleshooter at Windows Settings > Update & Security > Troubleshoot > Additional Troubleshooters > Windows Store Apps.
3) Try to Reset or Repair the game in Windows Settings > Apps > Apps & Features > [Name of game] > Advanced Options > Reset or Repair. Restart PC.
4) If that's not enough then uninstall the game from the same place, restart PC, reinstall the game from MS Store Hub (three dots at top right of Store app) > My Library.
I hope this helps. Feel free to ask back any questions and keep me posted. If you'll wait to rate whether my post resolved your problem, I will keep working with you until it's resolved.
______________________________________________
Standard Disclaimer: There are links to non-Microsoft websites. The pages appear to be providing accurate, safe information. Watch out for ads on the sites that may advertise products frequently classified as a PUP (Potentially Unwanted Products). Thoroughly research any product advertised on the sites before you decide to download and install it.
