Gale Andrews wrote: cut or copy and paste from the 44100 into the 48000 Hz.
Ah ha! That's the bit I was missing.
I can reproduce the bug on Linux and XP.
I often paste audio clips of different sample rates, but I always deal with them as discrete clips.
The bug only appears if audio is pasted
into existing audio that has a different sample rate.
At least this points to an easy workaround for tablo:
Before pasting the copied audio, click at the place where you want to paste it, then press "Ctrl+I"
This will "split" the audio in the track that you are pasting into.
You can then use Ctrl+V (or select "Paste" from the Edit menu) to paste the audio.
The audio will now be pasted as a discrete audio clip and will play at the correct speed.