when anchored objects (such as column Text or line numbers) are anchored in a Text using the options "Paragraph border" and "paragraph Shading" the borders and Shades will "randomly" disappear, or new border-lines will appear (when more then one paragraphs are merged, the lines always appear between the different styles, even though they work fine again when the object is de-anchored). Sometimes the appearance doesn't change when an object is anchored, but when the anchored object is edited (for example, when the size of the anchored object is changed).

This is reproducable on my Windows 10, using InDesign 15.1.4.

The problem also sometimes appears when an object is anchored in a text using Paragraph border/ shading, when text anywhere else in the same story is edited.

This issue continues to be seen in a PDF, which makes it really hard to have a stable document using this paragraph style options.