First, let me start with the specs.
Car is 2004 mazda sedan, 1.6 petrol engine with 5 gear manual, FWD, European version. Car has 148k km on it, so around 92k miles.

For some time i have been having this issue, when in complete stop, i cant engage 1st gear (sometimes no gear at all) , if i apply some force, it will go inBUT, revers always works.
And as a note, iif i blip the trottle even 200rpm with clutch disengaged, or about to disengage it, it goes into gear
When the car is moving, it's no problem to switch to any gear, even 1st gear works beautifully if the car is rolling a bit.

When the car is off, transmission works fine, can select all gears.
I did the following test, with car ON, press clutch pedal, it wont go into gear, turn off the car, it goes right in the gear.

I thought maybe my clutch is dragging, but the clutch biting point is always in the middle, and i never had slippage or any grinding on the clutch. If i accelerate hard in any gear, it holds up good.

One important info, when the car is cold, gear enagement is smooth and no issue, as soon as i use the clutch a few times, it gets worse. I tried pumping it, does not help, i tried bleeding (gravity bleed), no air came out, again, let me mention, the clutch biting point is in the middle, and works fine, when driving.

I measured the slave cylinder extension when pressing clutch, it's always the same. One thing to note, i think the issues started when i got the clutch line replaced (old one started to rust near slave and was quite well off). But again, clutch grabs always in middle.

Took it to a shop, the guy tried it, it worked fine, i came to pick it up, it worked fine.

Any opinions welcomed