To add to what kjpetrie said, one of the main reasons for the problem is user error, when installing a second Linux OS. With the first Linux OS, it's necessary to create a swap partition, which then gets a UUID number. With additional Linux OS, there is no need to specify a swap partition, in any manner, during the partitioning phase; if one exists, the new OS will use it as is. If the user selects the existing swap partition specifically, when designating partitions to be used for the new installation, during the partitioning phase, the installer will then reformat the swap partition, thereby giving it a new UUID number. All other installations using the old swap UUID will now need to have their initrd image updated.
When I add another OS, I only designate the new / partition, and set it to not be formatted, as I do this prior to the installation. The only time I mention the swap partition is during the grub install phase, when I set the resume partition for the grub stanzas. I have yet to have an existing swap partition reformatted by an installer.