If there are no other issues like a limited amount of system memory, running a deprecated version of Photorec, configuring Photorec to try and recover all types of files instead of specific ones, then if you are certain that the files you recover actually are
saved to this separate recovery partition then the total size of the files to recover may be larger than the size of your recovery partition. If that is not plausible I would run Photorec with the logging switch in the hope it might reveal clues. If not I would run strace on it and see if that supplies clues. If not I would boot the machine with a CDROM and run the "known good" version of Photorec from say the old the Helix 2008R1(2.0) ISO
(MD5 hash 93a285bfa8ab93d664d508e5b12446d3). I hope you umounted the partition as soon as you recovered the deletion, didn't mount it again and made a bit-level copy of the partition before doing anything else.