I have read several walkthroughs and watched several people do it on youtube.
When you leave the kitchen up the ladder and through the water with the queen, you are supposed to turn left, and then move forward again. The walkthrough says so, and I WATCHED people do it. But every time I try, the guards are there at the second screen. I go left, then straight, but at the end of walking straight once, the guards get me. I can't figure out another way...this is how you are supposed to do it. I'm lost on how to progress.

I have almost the same problem/bug

I can't complete this section of the Carbonek Level.

When leaving the cave with the princess, Seth needs to go back and meet hector near the flyer. I can't complete this part of the level, which gets into one of two situations:
1. one of the royal guards arrests Seth and the princess (even when going through the suggested path in a walkthrough) -and the section starts over

*I added a screenshot of the suggested path from this walkthrough in the attachments (walkthrough from IGN website)
2. sometimes, when reaching the end of the path to meet hector (where he supposed to be waiting), but the game doesn't continue to the cutscene when hector is greeting them.
*I added a screenshot where I stand on the location where hector needs to be and looking towards the flyer, there is nobody there.

I used the original game from GOG and also patched the Extended cut version..

With the Extended cut- the guards arrest Seth on the suggested path -too many times.

On the original GOG game- I can't get to hector where he supposed to be waiting...

Is this problem caused by an internal file error? or something else?

I use Windows 10 64bit version 1909

Thank you for your advice.

When installing the Extended Cut patch, what difficulty level did you choose? If you chose the option "I've played Atlantis many times" (or something like that) then it's the higher difficulty level and the way to escape from Carbonek looks different