I cannot offer any solutions. However I experience the exact same thing. It happens often that nothing comes to mind and I am a quiet person as a result. People don’t understand and believe that something is bothering me or that I am aloof. My brain just does not work the same. People say I am hard to get to know. My response is to tell them just ask me a question then I’ll know what we should talk about. I recall watching TV with a women I was dating and after a few hours of silence she looks over at me and says “speak”.