I also had the same problems as mentioned above. This morning (CEST) before work the wallet conversion started and the screen was still giving me the bouncing balls. So I closed Brave (and PC) and went to work. I started Brave about two hours back after coming home. And still the bouncing balls and a notification thanking me for my monthly donation: something that should not happen for 10 more days.
I switched off the Brave Payments and switched it back on again. I again got a notification that my payment was processed, but this time it was followed by the notification that the wallet conversion would be ready in 30 minutes.
Now however I see something that does not compute. My wallet now contains 0.01 BAT. I added 0.01002600 BTC to my wallet on 26 September, so the conversion did not work. Apart from that my monthly payment now stands on a whopping 25 BAT (140860.00 USD). My other choices are 50, 75 and 100 BAT.
I tried to recover my old wallet, but to no avail: the keys are not accepted.
Any idea what I can do to fix this? Because following the link you supplied does not give me any new insights or solutions.
Update Channel: Release
OS Platform: Linux
OS Release: 4.10.0-37-generic
OS Architecture: x64