debugging - Not able to debug/trace a large Win64 application -

i have large application of around 1 million lines of code, 500 .dfm , .pas files spread out many folders.

not many user components used, few. no external packages used/embedded.

when try trace or breakpoint win64-bit exe target, not stop, breakpoint line stays green.

as 32-bit target exe, no problem @ all.

this run on x64 os.

if try small basic test application (around 1000 lines) can trace win64 target.

same behavior xe3, xe6 , xe7.

i discarded config files project , used dpr file load, config reset scratch.

i can compile, no problem, same issue there, no way trace it. breakpoints stay green.

this annoying because have no means debug / trace application.

any workaround highly appreciated.

i have no clue comes from.