I can confirm the bug was not present in 5.1.7.1 .
For a travel agency web site I have two nested repeaters (Room Type > Prices) so that they can insert prices for double room, triple room, etc and for several dates for each room type.
The price repeater has conditional logic to show the price field only for the selected room type; it worked perfectly till yesterday, when I updated to 5.1.9.1 .
Now every time I try to save a post, I get an error stating that 6 fields are missing (e.g. if I typed values for double room prices, the missing fields are for single, triple and quadruple room price).
Fortunately I was able to downgrade to 5.1.7.1 from a backup.
