Mlc Thank you very much for your detailed description. We fully understand your situation.
The EmuELEC 4.8 system and the 256GB game SD card you are using are not officially provided by Beelink. They are third-party pre-configured game systems. We do not have the relevant technical documentation for this customized game system, so we are unable to troubleshoot the external drive mounting issue for you.
We recommend you reach out to the original seller who provided this EmuELEC game system for further technical support. They are familiar with their custom setup and can give you the correct guidance for adding external game storage.
We appreciate your understanding.