The xStation needs a well performing SD card that can deliver CD data reliably in under 6.7ms.
To help the SD card, format it using the official formatter tool. It really helps with access times:
https://www.sdcard.org/downloads/formatter/
The tool will automatically choose exFAT (for larger cards) and set correct alignments and cluster sizes.
If the issue persists:
MacOS likes to place metadata files on external media, which make it hard for the loader to find the actual games. This behaviour can be turned off (thanks @Thanos :))
defaults write com.apple.desktopservices DSDontWriteUSBStores -bool true
The most likely cause for reset signal issues is that the QSB reset point doesn't connect well (or at all) to the PSX mainboard.
An alternative test point exists near the expansion port.
It is okay to solder an additional wire from the QSB to that reset point to fix the issue.
Thanks to the modding community, we now have test point images.
You can use them to verify that each signal is soldered down properly.
The currently most comprehensive images have been created by mmmonkey. Thanks!