Procedure to produce bug.

1.  Open Writer document, insert a few (e.g. three) blank pages.
2.  On the last page, insert a shape, then right-click on shape to "Add text box".

Test #1 (Set View > Text Boundaries)  Click on the text boundary in the shape.  The shape is selected. (while not necessarily expected, not a surprise).

3.  Add a new shape (or textbox), and group the new shape with the previous shape that has the added text box.

Test #2.  Click on text boundary of textbox.  In contrast to Test #1, the cursor is now moved to the top of the document.

4.  Ungroup the two shapes.

Test #3. Click on text boundary of textbox.  In contrast to Test #1, the cursor is now moved to the top of the document, even though the original shape is no longer grouped (as in Test #2)

Expected result:  Nothing happens when clicking on text boundary (beyond making selecting the shape)

Additional information:
1. This has happened with grouping a shape with a textbox, a shape, and a line.
2. I notice that when a text box is added alone then Text Boundaries are not shown -- in contrast to when the text box is added to a shape with a right-click "Add text box".

Tested with:
Version: 6.3.3.2 (x64)
Build ID: a64200df03143b798afd1ec74a12ab50359878ed
CPU threads: 8; OS: Windows 10.0; UI render: GL; VCL: win; 

and

Version: 6.4.0.0.beta1 (x64)
Build ID: 4d7e5b0c40ed843384704eca3ce21981d4e98920
CPU threads: 8; OS: Windows 10.0 Build 18362; UI render: default; VCL: win;