Problem in the catches of front doors - Audi A6 (96)

Hi All,
I have a tedious problem in my Audi A6 -96. I cannot open the front doors by using the catches inside the car at all. Consequences: I have to use the back doors to get out of my car or alternatively slide the
window down and use the handle outside. Usually I prefer the latter one :).
Initially I thought they were frozen, but that's not the case. The problem arose to the both front doors at the same time and the central lock works just OK, no matter if I use the key or the knobs. "Look and feel" of the catches is normal as well.
Another oddity in this: I tried to "reset" the central lock system by removing fuse but there seems to be no fuse for central lock at all. I went all of the fuses through one-by-one and central lock worked always!??
Any glue?
regards, John

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