Hi guys.
I know this is an old post but hopefully someone will find this helpful.
I have a 2016 octavia and this happened to me for the first time. All very annoying. I couldn't get the solution to work as above, however this one did work. https://www.briskoda.net/forums/topic/103034-drivers-seat-memory-not-working-fixed/
The only thing to note that I did different was.
Ignition on.
Move seat forward (when it stops press forward again and it may move another could of cms)
Tilt front of seat down
Lift back of seat up.
When at max on both (hold the front of the switch down while holding the back of the switch up)
Recheck a couple of times and hey presto a "bong".
Then i could save seat positions again and it worked.
Please note I didn't change the back rest at all.
Good luck