2015 Versa 55k miles: clutch pedal travels to the floor. Replaced the master cylinder with an after market one. Bled out the system, nice full clutch. Overnight, pedal loses pressure. No visible leaks & no fluid loss in reservoir. Took the vehicle to an experienced mechanic thinking it would be the slave cylinder. He wanted to put a Nissan MC on. Same issue. He doesn’t see anything pointing towards the slave cylinder. I’ve read about the fluid reservoir causing this type issue… also possibly an inline dampener. We’re frustrated.