Reset bit on siemens plc

Good morning,
I’m using version 7.9.16 and I have some problem during reset/write tag.

I see this on transaction group, but probably exist for all job of writing tag.

When I go to reset one bit from 1 to 0 , if I check instantly value I see this 1-0-1-0 .

Why this happen?

How I can avoid this?