Bug: Moving org-inline-tasks produces error message [9.3.6 (9.3.6-elpa @ /home/c.hemminghaus/.emacs.d/elpa/org-9.3.6/)]

[Christian Hemminghaus <chrhemmi@gmail.com>]

Hello everyone,

I ran into an error message while composing structured text with
org-mode using org-inline-tasks. The error appears when moving around
inline tasks in my document.

Here is the example:

# ##### BEGIN EXAMPLE

This is a paragraph in my document.
It may contain multiple lines.

*************** TODO Inline Task
*************** END

This is another paragraph.
May be multiline aswell.

And a third paragraph.
May be multiline aswell.

# ##### END EXAMPLE

Putting the cursor on "Inline Task" and hitting org-metadown should (at
least in my opinion) swap the inline task with the second paragraph and
hence produce the following:

# ##### BEGIN EXAMPLE

This is a paragraph in my document.
It may contain multiple lines.

This is another paragraph.
May be multiline aswell.

*************** TODO Inline Task
*************** END

And a third paragraph.
May be multiline aswell.

# ##### END EXAMPLE

But instead it produces:

# ##### BEGIN EXAMPLE

This is a paragraph in my document.
It may contain multiple lines.

*************** END

This is another paragraph.
May be multiline aswell.

And a third paragraph.
May be multiline aswell.

*************** TODO Inline Task

# ##### END EXAMPLE

Together with an error message:

org-show-children: Invalid regexp: "Invalid content of \\{\\}"

As swapping paragraphs with inline tasks works the other way around, I
think that this is a bug. Since I am not much familiar with elisp, I
would appreciate a hint how to fix this bug.

Best regards,
Christian

Emacs  : GNU Emacs 26.3 (build 2, x86_64-pc-linux-gnu, GTK+ Version 3.22.30)
 of 2019-09-16
Package: Org mode version 9.3.6 (9.3.6-elpa @
/home/c.hemminghaus/.emacs.d/elpa/org-9.3.6/)