Ok, I’m also new to custom models/characters, and I’m not sure why it is invisible. But, how are you importing it in? What type of file is the mesh? FBX? OBJ? Also, through the Home tab, click this:
Ok, so then I uploaded my own character as an FBX file that is already rigged, not sure how you rigged yours. I auto-rig mine through Mixamo. But, it should appear something like the following, and I want you to click this button.
which should show you what the rig looks like:
Yet, your model should appear there, and you should be able to see and visualize what the rig looks like before even importing the character.
Ensure this is set to custom:
Also, import it as a model, unless you aim to do something else.
Can you also send how and what method you use to upload your custom character? Also, through using this method, does your character appear? If they don’t, it must be a problem related to Blender. Maybe, the mesh is inside out. But, if it does appear, and then it disappears once it is placed in the workplace then I suggest you try uploading any other 3D model and drag any mesh from the Toolbox to your Workplace and see if they vanish or not. If the problem continues, try to point out at which stage it does, and show us the way you upload your character in general so it’s easier to identify the problem. Thank you, and I hope this helps! Good luck!
Edit: I don’t suggest uploading your character through a plugin but through Roblox directly, and you can watch YouTube tutorials on how to create a HumanoidRootPart, so you can animate the character in the game.