Bug with proxy files and ips adaptation
If you change the frame rate of a video files after you create the proxy the edit is different in the timeline with the proxy and the original media.
More your in point is far more the clip in the timeline change between orignal & Proxy files. I think the change for the frame rate is not apply to proxy files. I found the pb with the latest CC2020 in juin 2020. It is very easy to reproduce the pb. Chose an 24P original media, create proxy, change the frame rate to 25P ad the clip in a new 25P with an in&out point. Change the viewer between Proxy/original the first and last picture change for every clip in the timeline with the same edited Framerate and change all your timeline coherence.
Talenton JeanMarc commented
Sometime I have to use video files shoot in 24P but my timeline and most part of the film is shoot in 25P so it's the better solution to play 24P at 25P in my 25 timeline. And I don't understand why if I change the Framerate of the original media, Première Pro doesn't change the proxy also.
In the same way If you interlaced footage and Progressive footage it's better to desinterlace all the interlaced footage in a Progressive timeline. This option doesn't exist in Première Pro at the file level. You can change it but only in the timeline. This is a west of time and a risk of error
What were you trying to accomplish, by changing the original media's frame rate, _after_ making the proxy?