I tried the first 2 methods, but to no avail:
1. Increasing mesh distance up to 2000, and max region loads to 3: no difference (even the min distance at which the blocks appear / disappear)
2. Turned dynamic mesh off, load (note: pillar was gone), turned back on: pillar was visible again
I might try your 'nuclear' option, but perhaps this should be filed as a bug? It happened to me a couple of times in A21 as well. Besides, I can imagine 'remembering' all these removed blocks can be quite a performance waster.