Vim/Vi and powershell in Docker causes scrolling anomalies

Having deployed a Fedora (FC24) docker image and a separate python (python 3.2) docker image. Both experience the same problem if I connect a terminal to the image e.g. "
docker exec -it fedora bash
If I open a file say /etc/bashrc or /etc/bash.bashrc with vi or vim I and then I start to scroll down with the cursor block the cursor at random points stops scrolling and vi command line (at the bottom of the terminal) shows:
?o
If I scroll away and then back again over those lines it stops again at the same point. That point seems to vary, so there may be 3-4 locations in the file where it will stop when scrolling and all appear to be normal bash code or comments, I can't see tell what is going on. Has this behaviour been seen before?

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