Hi @vlig96. thanks for taking the time to upload the project and with the additional details. I have been able to compile and execute the program, create an installer also but was unable to reproduce the strange issue with the start button you referred.
I would therefore recommend if you could share the installer file you created directly and I will try with this one. Might also be an idea to get another colleague to test your program on another system to see if we can narrow down where the problem may be arising. Thanks for your patience whilst we try to provide you a solution.