QGIS cluster character symbol visibility based on cluster size

Question

I want to display the cluster size with a condition : I don't want to display this information for small clusters. The expression is working fine but I don't know I can add else...

case 
when @cluster_size > 30 then @cluster_size
end

Is my case, cluster size of the clusters with a size > 30 are displayed. BUT cluster <30 are labelled with a A letter AND I want to display NOTHING.

Not working :

case 
when @cluster_size > 30 
then @cluster_size
else @cluster_size = NULL
end

Returns me 0 but not empty :

case 
when @cluster_size > 30 
then @cluster_size
else @cluster_size = ' '
end

If I remove A letter from the assistant, nothing is displayed.

Answer 1

I am not sure what is wrong in your case but I can confirm that Else '' removed the A and got empty cluster:

case 
when @cluster_size > 30 then @cluster_size
else ''
end

Output

I am using QGIS 3.10.4.