Description:
When importing a CSV file from a command line (eg. by double-clicking on it in File Manager, or downloading a CSV file in web browser), while Calc was last used in maximized window, after the initial import dialog the application window is invisible, only the window top bar appears.


Steps to Reproduce:
1.The setup: Ubuntu 20.04 with GNOME Flashback/Compiz session, LibreOffice 6.4.4.2
2. Make sure Calc was last used with maximized window (open Calc, maximize window, close).
3. Open CSV file via command line, eg. by double-clicking it in File Manager, or downloading a CSV file in web browser and choosing to open it in LO


Actual Results:
1. The usual CSV import dialog appears (this is correct).
2. After clicking OK, only Calc window header bar is visible. The application window does not appear. However, despite of being invisible, the application seems to actually work - if you "blindly" click eg. on the place where menu options should appear, the pull-down menus appear, if you right-click anywhere on the screen, the context menu appears. However, in the place where the application window content should be, the previous content of the screen is visible.
3. The application can be minimized, un-maximized and closed using the controls in the header bar. When un-maximized, it becomes a very small window (36x67 pixels in my case) - regardless of the previous size of the Calc window before being maximized - containing only the close button. When expanded, this window is visually empty but still a working application as specified above.

Expected Results:
The application window should open normally in maximized mode.


Reproducible: Always


User Profile Reset: Yes


OpenGL enabled: Yes

Additional Info:
The issue does not occur if Calc window was NOT maximized, so the workaround is to open Calc, un-maximize window if it was maximized, close and then try to double-click on a CSV file or download a CSV file from the web. Calc window appears correctly.

Disabling hardware acceleration does NOT help. But just in case, here's OpenGL information from "glxinfo|grep OpenGL":
OpenGL vendor string: NVIDIA Corporation
OpenGL renderer string: NVS 315/PCIe/SSE2
OpenGL core profile version string: 4.6.0 NVIDIA 390.138
OpenGL core profile shading language version string: 4.60 NVIDIA
OpenGL core profile context flags: (none)
OpenGL core profile profile mask: core profile
OpenGL core profile extensions:
OpenGL version string: 4.6.0 NVIDIA 390.138
OpenGL shading language version string: 4.60 NVIDIA
OpenGL context flags: (none)
OpenGL profile mask: (none)
OpenGL extensions:
OpenGL ES profile version string: OpenGL ES 3.2 NVIDIA 390.138
OpenGL ES profile shading language version string: OpenGL ES GLSL ES 3.20
OpenGL ES profile extensions:

A hint to reset user profile does not apply to this issue, because by default, without an user profile created, Calc does NOT start with maximized window, and the issue occurs ONLY with maximized window.

However, after resetting user profile the effect is also unusual because by default Calc starts in a very small window that needs to be expanded to do anything (that applies both to the case described here and to regular launching of Calc from the menu) - in my case this window is 36x67 pixels, as in the case when Calc is un-maximized after importing CSV file. I will attach a screenshot showing this window.