Codegen complaining about cell-array assignement

Hello,

I am trying to generate a MEX file from my code, but I can't seem to figure out why codegen reports this error. I've tried to work around the problem in several ways but nothing seems to work. What i'm trying to do is constructing a cell array which entries are cells themselves.

Specifically, codegen says the following:

"every cell-array element contained in 'allvalues' (must) be assigned ... Check assignements to element(s) allvalues{:},allvalues{:}{1,1} ... allvalues{:}{1,4}."

The code is the following:

function rehash(obj)
            
            allkeys=getkeys(obj);
                     
            %Get all values
            allvalues=dim_singleton_cell(length(allkeys));
            
            for j=1:size(allvalues,1)
                %Get all values
                [temp,~]=get(obj,allkeys(j));
                
                allvalues{j}=temp;
                
            end
            
            newcapacity=ceil(2*obj.capacity);
            obj.capacity=newcapacity;
            clear(obj);
            
            %Rehash
            putAll(obj,allkeys,allvalues);  
end

allvalues is a {N,1} cell array (the coder.Type is [Inf x 1] ) where each entry is a {1x4} cell array (coder.Type is [1x4]). The function dim_singleton_cell creates a {N,1} cell array with entries {int32(-1),...,int32(-1)}.