That's the continuation of #906
I was able to start the migration with zombie-bite (a tool similar to chopsticks but it produces the blocks at regular 6s cadence, not on-demand as chopsticks does). There I was able to start and run the migration (over 200 blocks for now) without any issue. It makes me think that an issue is on chopsticks' side.
@xlc will you have some spare cycles to look deeper into it? If I can help you in any way, just let me know!