The current bid price of a listing never updates after the listing is added to my buying list. It remains exactly as it was at the time it was added. The only way to update it is to use the 'Refresh' button on the Snipe screen, on a per item basis - this is terribly clumsy and time consuming.

Please set this value to update automatically at a user chosen interval or add a global refresh button at a bare minimum.

The fact that the auto update feature is missing is totally baffling. Why even have a Current bid display if that's not what it displays?

This is by design. It will refresh when you click the "Refresh" button.
Please note the current bid does not affect the actual sniping.

This is a sniper, not a monitoring service.
If you need to monitor prices in real-time, please use eBay directly for this.

would it be possible to show the current bid in the overview. and a refresh button to update all items?

It's technically not possible to have it shown in real time.
If you must monitor a price in real-time, please use eBay directly.

As I mentioned above, Myibidder is not a monitoring tool, it's a sniper to place bids on last seconds.
Please keep it in mind.