Time for soem trouble shooting !
Instead of burning the project to a blu ray, burn (encode) it to an ISO (image) file. This separates the encoding from the burning so your computer does one thing at a time. We should be able to tell if it is an encoding (project) issue or if it is a burn issue.
Once the ISO is completed, you can select to play it to see if you still have the issues or if that was a fix. If the ISO is OK, then you can burn the ISO to a BR.
Make sure it is a a top quality BR; usually store brands or cheap BR are no very good and can have defects so the burn doesn't go right.
I'm going to assume that you have done all the maintenance on the computer (get rid of junk files and prograsm you don't use), update th drivers or firmware for the burner, the vido card/chip and the audio chip.
I'm aqlso going to assume that you are doing nothign else when you are encoding the ISo file - no games, no e-mail, etc.
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BoilerPlate: To posters who ask for help -- it is nice to thank the volunteers who try to answer your questions !
Anything I post unless stated with a reference is my personal opinion.