Checkmarks Not Showing for Latest Added Songs in Large Playlists

[blabala22]

Free plan, windows web.

I have a playlist with 400 songs. When I view songs from this playlist in another playlist, some of them don’t show the checkmark indicating they’re already added. However, after adding the last 50 songs from my 400-song playlist to another playlist, I noticed that those songs now correctly display checkmarks when viewed elsewhere.
Is there a limit on how many songs Spotify checks for duplicates in a large playlist, if there is, what is the limit? Is it 200, 250? I tried again with a playlist that had 231 songs, last songs didn't have checkmarks. Than I tried this, I added the songs 250-260 from another playlist that didn't have checkmark even though they are added to a large playlist of mine, to an empty playlist, and I saw the checkmarks. 

Normally, selecting all songs from large playlists with 250+ songs on web version does'nt work unless you slowly go page down and detect/load the songs and do Shift+A.

But there is nothing to detect here, I add songs to my playlist one by one. What is there to detect? Why are there songs without checkmarks in my large playlist?

When I added all the tracks from "Street Fighter 6 Original Soundtrack" which had 284 songs, all of them still had checkmarks when I checked back the original album. So maybe this problem only occurs when songs are from different albums? Doesn't make any sense.

I also did this. I created 2 playlists from my 450 song playlist, I divided the songs into 200-250 in two playlists, and all songs from that someone elses large playlist has checkmarks now. I fixed it this way but it forces me to refresh the original playlists page to check the checkmarks, be in doubt all the time on if the songs are added to my playlists properly so that I can see their checkmarks on other playlists, and divide playlists.

And I already had this problem with checkmarks https://community.spotify.com/t5/Other-Podcasts-Partners-etc/I-got-a-few-problems-with-spotify/m-p/6...