If you look up PI3-kinase p110-delta subunit inhibitor on the node synonymizer, you'll see that it has the identifier CHEMBL.MECHANISM:pi3-kinase_p110-delta_subunit_inhibitor. This is related to: https://github.com/NCATSTranslator/Feedback/issues/1039
This will likely become a non-issue after moving to NodeNorm, but in case you wanted to fix this