I was using JoeLister to sync amazon.co.uk to eBay.co.uk
It basically works, but has a lot of annoying quirks.

My prices for Amazon or eBay didn’t match. the sync is too infrequent, and when updated is still wrong.
so you have to check in amazon on ebay all the time.

My prices kept flipping between $ and £, but at the same price. really confusing.

The other thing that got me was that I ran into an error while listing to eBay which prevented me listing anything.
it was related to postage. I didn’t have anything in my settings that seemed to cause this issue.
I contacted eBay and they said they’d made changes that week which cased it, and the vendor needs to reach out to them for help in order to fix their app to work moving forward.

I notified JoeLister about eBay updating their site and told them to reach out to them. Ignored…
In the end, I got fed up, thought f##k these guys and am going to use an alternative company at some point. I’ll focus more on just selling on/via Amazon with items I ship to fba, and will do my own eBay fulfilment.

I’m actually disgusted at how crap the company is on support.