Bandai Visual has noted release date updates for Vol.2
(1/29 to 2/22) and Vol.3
(2/22 to 3/22).
It's probably safe to assume that the subsequent volumes (at the moment Amz JP have them as -> v.4: 3/22, v.5: 4/24, v.6: 5/28) are delayed a month as well.
Vol.1 release date did not get changed.
- Vol.4 (3/22 to 4/24)
- Vol.5 (4/24 to 5/28)
- Vol.6 (5/28 to 6/21)
EDIT 2: via ANN
The staff explained that the delay was to ensure the quality of the Blu-ray volume's original video anime short, "Survival War!"