Man. I am SO GLAD that you are writing this because I am having the same issue and honestly I am starting to get very, very worried about my AMS motors.
I’ve only had my X1C and AMS for a month, but already on a refill and just like you I followed all the instructions to spool it on a used up spool properly.
Well, no matter what I did, I had the same exact issue as you. There was a massive gap on the one side of the spool and tons of cross over. I did also have some feeding funnel protectors printed with little bits of PTFE tubes sticking out of them (in the ams) to help protect them against wear. But despite this extra flexibility for the filament, this refill has been an absolute NIGHTMARE.
It’s constantly binding because it veers off to the left side almost instantly during printing, gets caught up in the gap on the left hand side and when I try to pull it loose after looseing the spool up a bit, it pulls up other filament from below and that causes even more issues.
You’d think that Bambu would have solid QA and wind their spools properly. I had an Elegoo printer before this, and used Elegoo branded filament. The stuff was cheap, but it was WELL wound - almost PERFECTLY and I never had any issues with it.
I haven’t had the same problem on regular Bambu spools as on the Bambu refill, and I don’t know if just like you maybe I am just unlucky, but I am about to send a ticket for this because it happens so often i am worried about the assist motor on the AMS burning out and then having to replace it at MY cost, when Bambu will probably try to tell me its user error, when they can’t be bothered to wind their filaments correctly.
I really hope this changes but at least for now I am glad I am not alone in this.