CDO

Recently I encounter a problem that CDO do not longer find some variables in a netcdf file, while NCO and ncview still show them. I could use the CDOs some time ok without any problems!?
with CDO I get:

$ cdo showvar MNB.gridinfo.nc
cdi warning (cdf_set_var): Inconsistent variable definition for lat!
cdi warning (cdf_set_var): Inconsistent variable definition for lon!
delta depth
cdo showname: Processed 2 variables [0.01s 23MB]

with ncdump -h I get

netcdf MNB.gridinfo {
dimensions:
rlat = 245 ;
rlon = 427 ;
variables:
float delta(rlat, rlon) ;
delta:units = "degree" ;
delta:_FillValue = 1.e+30f ;
delta:long_name = "angle of re-rotation back onto geographical grid" ;
delta:coordinates = "lon lat" ;
float depth(rlat, rlon) ;
depth:units = "m" ;
depth:_FillValue = 1.e+30f ;
depth:long_name = "water depth in WAM simualtion" ;
depth:coordinates = "lon lat" ;
float lat(rlat, rlon) ;
lat:units = "degrees_north" ;
lat:long_name = "geographical latitude" ;
lat:standard_name = "latitude" ;
lat:coordinates = "lon lat" ;
float lon(rlat, rlon) ;
lon:units = "degrees_east" ;
lon:long_name = "geographical longitude" ;
lon:standard_name = "longitude" ;
lon:coordinates = "lon lat" ;
double rlat(rlat) ;
rlat:units = "degrees" ;
rlat:long_name = "rotated latitude" ;
rlat:standard_name = "grid_latitude" ;
double rlon(rlon) ;
rlon:units = "degrees" ;
rlon:long_name = "rotated longitude" ;
rlon:standard_name = "grid_longitude" ;

Until now the warning messages " Inconsistent variable definition for ..." was never a problem, maybe now?

Does someone have an idea how to fix this?

If it helps to find the problem I uploaded the file.

Kind regards
Nikolaus