Ouch. We don't test updating old systems to the current one. We only test updating the previous system, 1.24. So we can not predict what happens when you skip several update steps. But 1.24 to 1.26 normally won't close trades - at least there is no reason why it should, no matter with which version they had been entered.

Maybe you had a too-low setting of the stop slider? This can cause sudden closing of trades, unrelated to the update. Another possibility is changing the Mode slider while trades are open.

But you can recover the losses with Z5 in such a situation. Check the entry positions of the closed trades. For every one of them, manually open a new trade at market, with the same lot volume and a profit target of the old entry price plus 20 pips. This will recover the $5000 realized loss, although you lose the spread, and those trades are not handled by Zorro.