Impress Start presentaion with mosaic effect

My operation system is Win10 1909 x64. Libreoffice version is 6.3.5.2 (x64)

I type a new impress file. Suppose I make the second slide like this.

If I start the presentation from the first slide, the first slide could be shown correct. Then I press next page (page 2).

It look like this. Then I go on to page 3. Same mosaic effect.

Then I press back to page 2. The page 2 shows correctly.

What shaoll I do to make it correctly? Thank you.

Try off the OpenGL: OpenGL - The Document Foundation Wiki

Otherwise you can try reset to default user profil:

Safe Mode or

https://wiki.documentfoundation.org/UserProfile

I wish you success!

Thank you for pointing out the problem. Yes, it was caused by the OpenGL. There is a more convinient way of disable OpenGL. Luckily it was also suggest by you.

In the Safe Mode, there is an option to disable the OpenGL.

Thank you again.