bloom filter was broken for the first element, if all of the following
conditions satisfied:
- they are created on INSERT (in thie case bloom filter hashing uses
offsets, in case of OPTIMIZE it does not, since it already has
granulars).
- the record is not the first in the block
- the record is the first per index_granularity (do not confuse this
with data skipping index GRANULARITY).
- type of the field for indexing is "String" (not FixedString)
Because in this case there was incorrect length and *data* for that string.