Rounded corners automatically being expanded when trying to edit shape

[birthdaybee]

Normally I can make a rectangle, round the corners then select a corner anchor to move and change the shape while keeping the integrity and editablilty of rounded corners. 
I haven't changed anything, but all of the sudden clicking on any corner anchor causes the shape to automatically expand, meaning each corner now has 2 rounded anchors. It's as if I'm clicking the Expand button, but I'm not. 
Any ideas what's happening here?

[Mike Witherell]

Why not post this question in the Illustrator forum, instead of the InDesign forum?

[birthdaybee]

Because I'm using InDesign, not Illustrator 😊

[Mike Witherell]

Ah, my mistake. I saw the word "Appearance" and didn't look carefully enough!

[Mike Witherell]

Your question has caused me to notice something that I had not noticed before:

When you select a rounded-corner graphics frame with the white Direct Selection tool, a new (new to me) frame adornment shows up on the upper right corner: a yellow square with a square dot inside it.

Clicking this frame adornment Converts Corners to Paths.

It is the same as clicking on Object > Paths > Close Path. 

When did this feature/detail show up in InDesign?

[Willi Adelberger · Accepted solution]

This is a limitatiom. If you edit a path or use a pathfinder command the corner effect is not available anymore.