Description of the Issue

When two subsequent lines are hidden one by one, hide-markers seemingly combine into one block, that's OK:

But when I try to expand it, the first line remains hidden:

And its hide-markers disappears. Line 2 got lost behind the scene.
You don't see it in the tab and can damage it accidentally.

Steps to Reproduce the Issue

1. Enter five lines into a new tab.
2. Go to line no. 2 and hide it (Alt-H).
3. See green hide-markers appearing on lines 1 and 3.
4. Go to line no. 3 and hide it too.
5. See closing hide-markers now jumping onto line 4.
6. Click the a hide-marker (any of the two).

Expected Behavior

I expected both lines to be revealed.

Actual Behavior

Only line no. 3 got revealed. Line no. 2 got visually lost.

Debug Information

Notepad++ v7.8.5   (64-bit)
Build time : Mar  4 2020 - 11:08:34
Path : C:\Users\saukrs\_\bin\npp.7.8.5.bin.x64\notepad++.exe
Admin mode : OFF
Local Conf mode : ON
OS Name : Windows 10 Enterprise (64-bit) 
OS Version : 1803
OS Build : 17134.1365
Plugins : DSpellCheck.dll mimeTools.dll NppConverter.dll NppExport.dll

Real time video:

Workaround

If this is an unsaved file, you can't just reload the content without losing part of it.
I worked around this by doing:

• Select All
• Cut
• Undo

Line no. 2 got back.