Black Screen when add captions

Hi im working on project and discovered when added captions to video, in one place   for about 3 secodns i have a black screen , when turn off captions or in rendering screen change burn in to video  to anything else black screen is gone. Im using v22.0  My laptops spec i5 GTX 1650
Also discovered when i change in project settings render to software it works fine but then rendering take ages.