icebergs are present but grid checksums are zero

[nikizadehgfdl]

CM4 model stdout has:

diamonds, bergs_chksum: read_restart bergs chksum=            1503455964 chksum2=            -564881530 chksum3=           -1273480993 chksum4=           -1273480993 chksum5=             322483758 #=                 88278
diamonds, grd_chksum2:    # of bergs/cell chksum=                     0 chksum2=                     0 min= 0.000000000E+00 max= 0.000000000E+00 mean= 0.000000000E+00 rms= 0.000000000E+00 sd= 0.000000000E+00
diamonds: Bergs found with creation dates after model date! Adjusting berg dates by        1 years
diamonds, bergs_chksum: before adjusting s chksum=            1503455964 chksum2=            -564881530 chksum3=           -1273480993 chksum4=           -1273480993 chksum5=             322483758 #=                 88278
diamonds, grd_chksum2:    # of bergs/cell chksum=                     0 chksum2=                     0 min= 0.000000000E+00 max= 0.000000000E+00 mean= 0.000000000E+00 rms= 0.000000000E+00 sd= 0.000000000E+00
diamonds, bergs_chksum: after adjusting st chksum=           -1254997837 chksum2=             254665629 chksum3=           -1181833352 chksum4=           -1181833352 chksum5=             198276612 #=                 88278
diamonds, grd_chksum2:    # of bergs/cell chksum=                     0 chksum2=                     0 min= 0.000000000E+00 max= 0.000000000E+00 mean= 0.000000000E+00 rms= 0.0

Why are the grd_chksum2 all zero?

Moreover what does the following NOTEs mean and should something be done to address them?

NOTE from PE     0: During mpp_io(mpp_read_compressed_2d) int field ine found fill. Icebergs, or code using defaults can safely ignore.  If manually overriding compressed restart fills, confirm this is what you want.
NOTE from PE     0: During mpp_io(mpp_read_compressed_2d) int field jne found fill. Icebergs, or code using defaults can safely ignore.  If manually overriding compressed restart fills, confirm this is what you want.
NOTE from PE     0: During mpp_io(mpp_read_compressed_2d) int field start_year found fill. Icebergs, or code using defaults can safely ignore.  If manually overriding compressed restart fills, confirm this is what you want.