If you downloaded an NTSC-U (American) format save for a modified English-patched ISO, it may not register unless the save file name matches the internal ID of your patched game disc. Rename or convert the save file if necessary. Maximizing the Experience: Post-Save Setup
For those looking to bypass the grind of Bleach: Blade Battlers 2nd
: Close MyMC before launching PCSX2. You can verify the save by booting the PCSX2 BIOS
Newer versions of PCSX2 allow you to use "Folder" memory cards instead of single files.