Occurs when using EUR pound symbol and Netherland regional settings.
This is working correctly and is a result of not fully configuring all multicurrency settings.
Documentation states: Multicurrency: Opportunity Pyramid - Amount ranges displayed on the Opportunity Pyramid tab of a designation appear in the base currency of the ranges.
We need to set EUR as the base currency in all areas. If you go to Prospects > Major giving setup (under Configuration in the Explorer bar) > Opportunity Amount Ranges tab. Then select a range bracket and click the Change base currency action. This is how the range base currency is defined. The opportunity pyramid converts opportunity amounts into that currency when it displays them.