Slow motion not working

[Leproducer]

 I shot a clip in 50fps (pal) at a shutter speed of 50, and I placed on a 25fps timeline. I select speed/duration and move to 50%.  The video stutters, no smooth slow motion!  I view it frame by frame and can see that it only moves every second frame and not using all 50fps slowed on a 25fps timeline.  I've been doing this for years without a hiccup, and now since the update, I have this issue which I cannot resolve.  (Maybe it's a sign I need to switch to resolve!) To make it worse, it's random, some clips will work and some don't without any setting changes. I can no longer use slow motion on the clips I want! Yes, I've doubled checked the metadata, they are all 50fps at a shutter speed of 50 but some act as if they are 25fps.  Has anyone else experienced this ridiculous Premiere phenomena...... and solved it?

p.s I also tried (Modify > Interpret) with the same result. 

I'm using SONY a7IV 50fps clips, could it be the camera, the metadata clearly says 50fps?

I can send a sample camera video file if anyone wants to try it. 

[Ann Bens]

Did you set Optical flow and rendered the clip?

(should not the shutter speed be at 1/100 for 50 fps?)

[Leproducer]

I shoot in 50fps and always edit in a 25fps timeline, so the 50fps shutter speed is correct in this case.  This gives me the option of slowing footage down at anytime.  Optical flow is not relevant as some clips still work in slo mo and some don't.  I think it's simply a bug and my only fix is to roll back.   

Having rolled back to the previous version, the problem is sill there, I'm stumped! 

[Gianmeinecke]

I have the same problem and I'm looking for a solution... For me it's both at 60fps in 30fps timeline and at 120fps in 30fps timeline...
The strange thing is that sometimes it exports smoothly but not always...

[Leproducer]

I feel better that I'm not alone in this. After a couple years of shooting 50fps smoothly, this anomaly only recently started, sometimes it's smooth other times it's not.  Are you using a Sony camera or other brand?

[Gianmeinecke]

I've done so much research in the last few days but I just can't find the error...
I work with the FX3 and the A7IV.

[Leproducer]

I've been in touch with Sony technicians, and they feel it's the software.  Now I'm not so sure it's Premiere, as when I import it into photoshop, my 50fps is still 25fps.  I tried a simple half speed edit in Canva's online editor, same deal.  I have no issues with 100fps, that slows down nicely.  Just 50fps is the issue and it's random.  I'll keep on researching but it's doing my head in as it's a big part of my work flow! 

[basil1891]

Try to adjust speed/duration right in the project bin, before placing the clip at timeline

[Gianmeinecke]

Unfortunately, this is not a solution for me. I often have to ramp the speed in my projects from normal speed to slow motion... what confuses me is that sometimes it works and sometimes not.

[Leproducer]

Same deal for me, still 25pfs.