How are you generating the table? Code at least.
You might be able to use one of the procedures that supports PRELOADFMT to include all levels of a format for a variable in a table. That would require 1) a custom format for the variable with all of the levels and 2) the appropriate syntax for using PRELOADFMT.
Each procedure that allows use of the PRELOADFMT option has slight differences in syntax requirements so the following is only one way.
proc format library=work;
value $source
'A' = 'A'
'B' = 'B'
'C' = 'C'
;
run;
data example;
input source $ value;
datalines;
A 123
A 5
B 43
B 18
A 8
;
run;
proc tabulate data=example;
class source /preloadfmt ;
format source $source.;
var value;
table source,
value*sum
/ printmiss misstext='0'
;
run;