When editing a set where there are multiple coins of the same type (such as US Mint Uncirculated Sets where the same coin type and year but different mints) only one coin of the type is retained. The others are deleted. After they were deleted I added them back then did another edit and the same thing happened.
This is from this set (unpublished): https://en.numista.com/catalogue/set.php?id=269
Please fix soon as I have a lot of sets like this to add.
