Currency Reverts to Calculated Price, not Fixed Price

We’ve turned on the Fixed Price setting as we have a set Euro price book alongside our default Sterling price book. Everything works fine with the currency switcher until we change the language. At this point the Euro price reverts to a calculated value (the rate set in “Rate + Exchange Fee” setting).

How can we ensure that the Fixed Price product prices are always shown on the product page, even when changing language?

We use WPML as a language changer…

Please help!

Image attached showing the change in price when choosing either Spanish or German language.