[DnD 5e OGL] Can't add spells to character

One of my players is running a Elf Shadow Monk, which gets access to the Minor Illusion cantrip at Level 3. Unfortunately, I can't add it from the compendium. I can add any spell to any of the other PCs. Is there possibly some setting that I'm missing on his Character sheet?

Sorry if you already fixed it but I had this happen to me and it was silly but you might be having a different issue. When I have multiple sheets up whether intentional or on purpose, sometimes in accidentally adds to the wrong sheet or none at all. Try having only his char sheet up

Thanks for the tip. I double checked, and that is not what is happening.

I've solved the issue. It was one of the two below that corrected the issue. My PC's sheet spell attack bonus and save DC were not updating from 0. Clearing the spell_attack_bonus and spell_save_dc attributes and updating the spellcasting ability updated them to the correct values. Any spells that I dropped got stored in the drop_category, drop_name, drop_data, and drop_content attributes. Again, clearing these allowed me to drop spells into the character sheet and have them show up.