I have a local install of WordPress for development with a number of themes I am currently developing.
There are custom thumbnail sizes set using
add_image_size( 'thumb-category', 220, 180, true ); on two themes (different sizes with different names).
The problem is this; I have theme A active, upload images and use as thumbnails. Sizes work perfectly. I activate theme B and thumbnails are the wrong size. Not a problem as the correct thumbnail size for the images do not exist so I use the regenerate thumbnail plugin to regenerate the thumbnails. Sizes then work correctly. I then switch back to theme A and the theme is using the custom size thumbnail from theme B. both image sizes do exists but it seems to always use the last custom size thumbnail generated no matter what the theme specifies.
The only way I can get the theme to use the correct size again is to regenerate the thumbnails. Which isn't a massive problem, just a pain in the ####! I have even tried manually deleting all the thumbnail sizes except the correct size and it still tries to load the thumbnail size from the wrong theme!
Is this the correct behaviour? i.e. using the last generated thumbnail Or should WordPress be looking for the correct size thumbnail?