I noticed a pilot who was ATLM88B on the Jan 2020 list, removed from the list for 11 months (Feb 2020 through Dec 2020), then back on the list Jan 2021 as NBCPLAB, then SLC320B Feb 2021.

It looks like they might have been out on PLOA?

Is it normal for people on LOAs to come off the seniority list immediately? Why do NBCSIC and NBCMIL stay on the list while NBCPLA do not?