Massive acknowledgements of events

Hello all
I’m currently recovering a ScadaBR which has been left unmaintained from 4 years. I have something like 1 300 000 active events. I’m looking for a way to make them inactive quickly. Fortunately, I also switched to a new server, so I have an “old” database to make tests with.
So I tried the following directly in MySql:

use scadabr;
update events set ackts=unix_timestamp(), ackuserid=‘1’, alternateacksource=‘0’ where ackts is null;
update events set ackts=unix_timestamp(), ackuserid=‘1’, alternateacksource=‘0’, rtnts=unix_timestamp(), rtncause=‘1’ where rtnapplicable=‘Y’ and rtnTs is null;

I’m puzzled by the result: once back in ScadaBR, when I’m asking for active events, ScadaBR can’t find anything, but the “Critical” flag is still flashing in the upper part of the window.
Thanks for your help