iOS dynamic height cell in tableview- issue with row 0 and 7

I am having a tableview in which I am displaying my data. As you can assume from the title, these cells are dynamic in their content, and so should their height be. Actually I got it working, but I have a strange issue with the row 0 and 7. These 2 rows take my entire screen, but when I scroll past them and go back again everything is fine. I am not sure but the 7. cell must be among the first cells that are being "dequed" when I scroll down. But as I said, this is just the first time they are being displayed, when I scroll again to one of them, everything is looking good (when filling the tableview with new data it is also fine).

I tried to reload the tableview twice when it is being populated for the first time, but without success. The presentation of the first cell I have fixed calling : self.tableView reloadAtIndexPaths ... when the table is being populated for the first time, and it worked, it has the height it should have regarding its size. But I still have the issue with cell number 7 (the above fix does not work for this cell, I assume because it is not being displayed at that moment) I am not using any fancy height calulation, just the iOS 8 feature:

self.tableView.rowHeight = UITableViewAutomaticDimension
self.tableView.estimatedRowHeight = 80

Is there a method, fix with which i can force the tableview to draw the cells again ?

Thanks