It is as you say, if after enabling it, somebody goes to comment.
Then of course that old post should and will go first. This is not my point.
My point and the problem is the moment i enable it.
The moment i enable it, ALL comments go first.
Even if they are older than any of the not commented posts.
Ghosting all the newer "not commented" posts.
That should not happen.
Example:
Position of Posts in Frontpage when NOT Enabled:
1) Post1 on 10 Jan 2019
2) Post2 on 8 Jan 2019
3) Post3 on 6 Jan 2019 with comment on 7 Jan 2019
4) Post4 on 4 Jan 2019 with comment on 5 Jan 2019
Posts in Frontpage change position the moment I ENABLE it:
1) Post3 on 6 Jan 2019 with comment on 7 Jan 2019
2) Post4 on 4 Jan 2019 with comment on 5 Jan 2019
3) Post1 on 10 Jan 2019
4) Post2 on 8 Jan 2019
Position of Posts in Frontpage the moment I ENABLE it IF it worked as it SUPPOSED to be:
1) Post1 on 10 Jan 2019
2) Post2 on 8 Jan 2019
3) Post3 on 6 Jan 2019 with comment on 7 Jan 2019
4) Post4 on 4 Jan 2019 with comment on 5 Jan 2019
I hope it's more clear now.