I cannot add or remove songs from my playlist.

[Paytonk326]

Plan

Free

Country

United States

Device

Pixel 3

Operating System

Android Pie

My Question or Issue

I am unable to add or remove songs from my main playlist. I tried on my smaller playlist that has about 30 songs and adding and removing songs worked with no problems, but my playlist with over 400 songs just keeps saying that the song is already in the playlist although it does not show up not play. When I try to remove a song the option to do so does not even show up. I tried reinstalling and restarting my phone but neither worked to solve the problem.