Hi Joon,
Before support jumps in to help you, I’d just like to point out that your software is in fact up to date.
The latest Roon OS version is 174, see here: Roon OS Release Notes and the latest Roon version is 401.
Is your iPad Roon version up to date? If so then I would try and close the app down completely (swipe up on the app switcher screen) and re-boot your iPad, then restart the Roon. Apologies if you have tried this already.
You could also try the “Configure Roon OS Devices” button and see if that helps.
Regarding your PC not showing up as an audio device, can you please post a screen grab of the audio tab on the Roon settings page.