I see it on my two machines - one running Windows 10 and the other OSX. Both the latest CC Premiere.
Here are the reproduction steps:
- Create empty sequence
- Open a clip into the source monitor, set in/out points to a subset of the clip. Insert clip into timeline
- Double-click clip on timeline to load it into source window. Play in-to-out to verify it plays the correct portion of the clip (shortcut <Ctrl><Shift>+Space)
- Use "Speed/Duration" function (shortcut <Ctrl>+r) and set value to 25%, which will increase the size of the clip
- Double-click clip on timeline to load it into source window again. Play in-to-out. It will play the wrong portion of the clip.
So, after a bit of digging, it seems that if your clip is already loaded in the Source Monitor, it will not reflect your speed changes until you reload it.
Close the clip in the Source Monitor, and reopen it by double-clicking it in the Timeline. It should work correctly then.
I'm not sure if this can be classified as a bug, even though it can definitely be confusing.
Perhaps Premiere needs to do an extra check after a speed change is applied to see whether the clip is already loaded in the Source Monitor, and if it is, reload it to immediately reflect the changes.
Edit: After a little more digging around, this definitely appears to be a bug. The behaviour is not consistent and sometimes it will work without having to reload the clip, but mostly it will not. Adobe definitely needs to look more closely at this.