You might have missed something during the install of UFT 12.50. I think by default it only installs the LeanFT engine and not the client, so you will need to install that portion for either Visual Studio or Eclipse (or both if you want).

Try this:
Since you already installed UFT 12.50, you can run a Change operation to do a modification.

1. Run the setup again for UFT like you are going to install UFT 12.50
2. It will detect that it is already installed. Click the Change option.
3. Scroll down and find LeanFT. Expand the tree next to it to see addtional options
4. Find the Client
5. Select the drop down next to the Integrations and select the one or ones you want.
6. Click Next and follow the prompts to do the change operation