You may want to check if the wheel-like piece with a notch locks when you push it with a screw driver. It is located in the door, in the lock. This notch works with the gap in the catch. It may be that the catch moved too far towards the chairs over time and this notch cannot reach the catch to lock. If this wheel-like piece with a notch does not lock - then probably you need to take a look at the lock in the door, I think.
Maybe a couple of tips when you adjust the catch that is in B pillar if you need to (what you describe sometimes happen when the catch travelled too far in, towards the chair, over time):
1. Use painters masking tape to mark the position of the catch on the pillar - place it alongside its edges so that you do not lose the "0" position where you started, to move the catch along the line you need to move it and to protect paint when you move the catch. Align the shims under the catch nicely before tightening the catch (if you have shims there).
2. When you need to align/make sure it is aligned - the pin sticking out of the lock in the door with the hole in the catch and to see how other parts in the door and in the pillar fit together - place masking tape just covering the face of the catch and then close door slowly, but not completely, while looking at the tape through the gap. When you open the door again, you will see the marks that the pin and/or other parts left on the tape vs. the hole in the catch. If your pin is e.g. way down vs. the hole in the catch - your door may be low on hinges, you may look at the gaps in metal sheet as the door closes to confirm - that is another story... I would not mess around with that myself.
3. Use the proper screwdriver for screws that are holding the catch. If you destroy their heads it will be difficult to unscrew them. Also - destroyed screw head may damage the chrome part attached to the door.
4. You will not need to unscrew the screws holding catch completely when you adjust the catch - just loosen them a bit to be able to move the catch with a little tap. If you, however, need to unscrew these screws completely for some reason - you should not lose the threaded nests of those screws, nothing will fall down the pillar, the nests will hold there. That is - if everything is as should be in your car.
Take a look at Technical Manual on this website.