The problem will be in your Mockup template post the template not a vidio it easy to believe you have a problem I do not need you to prove you have a problem. You also most likly fd not want to to use Fit image unless you do not wast to loose any image an introduce boarders. Your Template most likel is not created well. So it will not work.
There are many free Good and many Bad free T-shirt mockups on the web.
The Mockup you habs may be designed to replace the T-shirt fabric not put a logo somwhere on the T-shirt. It looks like the smar object cover all of the T-shirt and is masked to the T-shirt,
Thanks JJmack for your insight. I will try with other free mockups I downloaded form this website.If it dosen't work ,I will pay someone on fivver to create Something for this script. Also,someone is selling a very similar script like yours here
I think you will find that script is not as versatile as mime. I saw noting in his video that indicated that his script can replace more than a single smarts object or could edit replacement into the mockup object with various options.
I think that script is a simple recpace content for one smart object layer. Like in the video.
There are some scripts on Adobe exchange for sale I feel look harder to use them mine.
I have no information at all if these are good.
Mine are Free and I feel well tested.
If a user is going to batch populate mockup there mock up templates must comply with the template design the script are programed to populate. The Mockup needs to be well crafted so it will be populated well. And some prep work will required so the replacements will be populated into the correct layers and that the correct set of replacement will be populated into the mock template.
My scripts are quite simple and dumb. They populate the Mockup Top smarts object layers via Replace Content or all the top smart object layers will be edited and updated with replacement content. From the top layer down to the none smart object layer.
My scripts know nothing at all about users files. The user is requited create replacement queue for each top smart object layers. The file in the queues are process in file name sequence, The sequences in each folder must match sequences in all the other folders so the correct set if replacement are populated into a template.