I’d guess LR 5.7+ coded things differently for displaying UI elements due to making things work better for HiDPI displays. Maybe there is some incompatibility with your video card or video drivers and LR 5.7+.
If you haven’t, try updating your video drivers from the video-card manufacturer’s site, rather than Microsoft.
Otherwise you can uninstall LR 5.7.1 and re-install LR 5.6 from http://www.adobe.com/downloads/updates
Thanks for the swift reply.
My drivers are all up to date and from the manufacturers. Reverting to LR5,6 is a bit silly isn't it, but it certainly is an option. Hope someone can reproduce this.
The radial filter and retouch pencil seem to work properly they show their "buttons" after adding or editing, so I have a hard time believing that the problem is due to the video card.
Make sure it’s not just that you need to press the H key to unhide the pins.
That was it! Thanks again! I can't remember having pushed the H-button, but then again, I learned something new today!