Hello everyone! How to you complete the weekly challenge of Bubble Trouble Chapter 2: Micro Machine! I have the 1957 BMW Isetta 300 export (STOCK) and I went to any Speed trap and reached the desire speed of 55mph/88.6km/h but its not letting me move on to the next chapter of Bubble Trouble! 
Try this:
Windows Settings → Apps → Apps and Features ->Forza Horizon 5 → In this Window go down to the Option: Reset to Default. And restarted my PC.
When it this don’t work do it the same Window, Repair and then Reset to Default and then Restart PC.
It can happen then on starting Forza Horizon 5 it says Sync Data… and this will take time. Don’t worry about it.
After that when i got back in the Game it worked for me.
interesting
Some people say that they needed to buy a new isetta, as current owned one wouldnt work on step 2.
For me, I found hitting 55mph wouldnt register, no matter how many traps I tried (8-9)
There is one on dirt where you go downhill, it allowed me to hit 56mph and boom, it completed and moved to step 3.
Obviously make sure car is stock (no tune) and even stock paint/livery - just saying what worked for me, but I didnt buy new car, my current isetta detuned was fine.-- just the stupid 1mph extra I needed to complete it
alight i bought an extra 1 but that crashes my game D: so you know where that speed zone is called?
Try San de las minas and even mountainside… both are downhill and you should have enough runway to get going to hit 56mph
good luck
ty