1P-LSD, one of novel lysergamides, is known to not react with the Ehrlich reagent within the expected time frame (minutes). Despite that, some users report that their samples do in fact turn Ehrlich reagent pink / purple.
How to test LSD: if you intend to use LSD (“acid”), first you need an LSD test kit to check it for adulterants. Pure LSD can be laid on any kind of blotter paper (or other surface) and can’t be identified by appearence. To test LSD use reagent tests Ehrlich, Hofmann, Marquis and Mecke in single-use or multiple-use test kits. To detect fentanyl or test for fentanyl analogs it’s recommended to use fentanyl test strips.