The updated 1449 version is strict. You cannot run mods made for tModLoader 1.4.3 or 1.4.5.
You must repeat the manual installation steps above, overwriting the old tModLoader files with the new ones from GitHub. 4. Key Features of the Updated Build 1.4.4.9 Compatibility: Full support for the "Labor of Love" update content. In-Game Mod Browser: download tmodloader 1449 updated