Hi @Samoreen, as Matt has mentioned above, the LR Publisher versions are designed to be backward-compatible between versions of Backlight. This is to allow customers to have websites with a mix of Backlight versions while updating sites. We don’t fully test them through past versions, especially not all the way back from Backlight 4 to 1.
I have had a quick try and found that our latest plugin does publish renditions at the correct size with BL1 sites. I can’t vouch that it will work perfectly across all of the functionality for BL1 sites.
Direct link to Publisher 6.1.3 (this should be compatible with Backlight 1, 2, 3 and 4):
https://get.theturninggate.net/install/download_lightroom_publisher/backlight-4-release/
Direct link to Publisher 5.2.2 (this should be compatible with Backlight 1, 2 and 3):
https://get.theturninggate.net/install/download_lightroom_publisher/release/