Clutch reservoir empty

[minesapint]

86 325i Cab.
Whilst driving yesterday gear selection became more and more difficult, just managed to get home. On checking the clutch pot it was empty.
Last year I replaced the seals in the slave cylinder, but not the master, (I read about doing both but thought I’d leave it). Less than a thousand miles covered since.
So naturally thought the master must have failed. But on checking today there is no sign of any leakage in the footwell, the carpets are clear, the master cylinder body, flex hose connection & dust excluder seal are all free of any fluid.
In the engine bay the hard line from end of master cylinder is dry, there is no fluid on the garage floor, nor any around the slave or bell housing.
Where has it gone? And how best to proceed.

[martauto]

They always say that it`s best to change the slave and master cylinders complete and together or this situation could arise, but I think you knew that .lol.
Where has it gone ??? no ideda mate, the fluid fairies ??

Start again with new of both units so you know they are right.

Mart.