While waiting for a fix from OP you can run the previous version by replacing with the 1.4 version plugin for the server targeting the older version in your config like this:
{
"mcpServers": {
"robloxstudio-mcp": {
"command": "npx",
"args": ["-y", "robloxstudio-mcp@1.4.0"],
"description": "Advanced Roblox Studio integration for AI assistants"
}
}
}