Have you personally verified on your channels ?Yes, some experts do not recommend uploading long videos to short video channels, they say it disrupts the channel's algorithm.
I have seen this being done by some creators but still the mentioned long video did not get much views.You could try connecting the two by turning popular Shorts into extended versions or playlists so the audience views both, but often times short form viewers won’t really engage in longer style vids.
I am also facing the same problem, audience would prefer to watch shorter videos, you can still keep it goingMy short videos give me lot of views and subscribers. But when I upload long form content on same channel, these subscribers do not want that content.