Give us a clear and concise description of the problem, and what you expect to happen

OmniCC works for everything except target debuff, verified in Luna Unit Frame, but also in Blizzard frames

Do you have any steps to reproduce this issue?

Connect to classic Era PTR Hardcore and try.

Are you getting any error messages?

no bug

What version of OmniCC are you running?

What version of World of Warcraft are you on?

What other addons are you running?

From fresh install :

Classic doesn't actually render cooldowns for target debuffs, so there's nothing for OmniCC to show text for.