Contour and anchor points sometimes visually disappear, although still accessible

[katjaq]

This is a bug report

What is the current behaviour?

During the refinement of a region contour, it occasionally happens, that once you click a point, the contour will no longer be displayed nor the anchor points, but if you remember where another point was, it is still accessible for click and drag displacement of the point and the contour path.
To get back the visual contour and points, often I save and refresh page and all is working fine.

I have not yet discovered systematic appearance of this behaviour, and am unable to reproduce it for now. It just happens from time to time. Often, I aim at adding a point to path, and after that, the contour disappears. But only sometimes...

What is the expected or desired behavior?

The contour and anchor points remain visible as long as the region is selected.

Version information (for bug reports)

• Browser + version: Chrome Version 86.0.4240.111 (Official Build) (x86_64)
• Your OS and version: iOS and MacOS Mojave 10.14.6