I am having this issue for past 2 days now.
I can't export reports to powerpoint.
Images are incomplete or I see error message of "This visual was not exported due to a timeout"
I've been using Power BI Pro for a year and I didn't have this problem.
I can't repro this issue on my side. Can you please share more detail?
In addition ,you can also take a look at limitation list:
There are a few considerations and limitations to keep in mind when working with the Export to PowerPoint feature.