russell_roberts:
Please try setting a value on the peripheral and reading it on the central
While I have done that in the past with the old Arduino 101 and a few others, I am going to say, "No thanks". I don't have the problem so I don't feel like I should write more code on top of the code and the lengthy posts I have already made trying to help you. Moreover, I don't get a sense that you are understanding what I have been saying. Maybe someone else can come around and do what you want them to do.
I am not sure, but I get the feeling that you may need to do some more background work and especially going through the ArduinoBLE .h and .cpp files as well as some background reading on BLE in general and also data type sizes on C/C++ (e.g., Data Types in Arduino - SparkFun Learn). Then, hopefully, these issues will become clearer.
Sorry that I could not be of help more and good luck with your project and education!