Invalid pH error Ligprep



I have been trying to use knime to create a library of ligands and use the Ligprep node to prepare the structures to use them in glide.
However, I can not seem to edit the settings of the Ligprep node.
An error ‘Invalid pH value specified (must be between 0.0 and 14.0)’ is displayed after clicking Ok, even if I did not change any settings at all or if I selected the ionization option ‘Do not change’.
Is this a bug or am I doing something wrong?