Webhook not running when using £ symbol

[1minManager]

I have created a wehbook in a workflow that essentially concatenates a load of stuff to create a URL which gets pushed to a SMS provider. All was working fine until I added the £ symbol here -

…
ENCODEURL(“12month warranty inspection. £”),
ENCODEURL([Sale_Price]),
…

Now the rest of the workflow still runs (it also creates 2 other seperate emails and adds 2 rows to another table). But the webhook bit does not. One of the emails it send to me serves as a kind of log email and also creates an idential URL. When I click on that URL, it works fine - the SMS arrives.

So I tried a few things:

…
ENCODEURL("12month warranty inspection. "),
ENCODEURL([Sale_Price]),
…
When I remove just the £ symbol the webook works fine

So I even coded the URL symbols myself
…
ENCODEURL(“12month warranty inspection.”),
"%20%C2%A3",
ENCODEURL([Sale_Price]),
…
Same issue. Workflow runs, but webhook within it doesnt

Anyone come across this before?