Sadly we might never know what the issues were, but for a computer chip the round trip to do changes is at least half a year.
If it's a couple of months delay, it's not a chip modification.
Six months would be very optimistic if they need to modify a chip. First a couple of months to fix the error and verify that nothing else has been screwed up, then 3 months in the fab, and a couple of months for verification.
Personally, from my working experience, I wouldn't count on less than 9 months TAT for a chip modification. And 9 months would be aggressive too.