Hello,
I faced just the same issue as you mentioned. This is Microsoft bug and I suggest you to get in touch and request a hotfix.
Following steps provide workaround (but it is unsupported of course):
1. Create a webresource and add this code:
function quoteonload(){
Mscrm.QuoteMainSystemLibraryWebResource.onTransactionCurrencyChange = function() {
!Mscrm.InternalUtilities.JSTypes.isNull(Xrm.Page.ui.controls.get("pricelevelid")) && Xrm.Page.data.entity.attributes.get("pricelevelid").setValue(null);
Xrm.Utility.alertDialog(Xrm.Internal.getResourceString("LOCID_CURRENCY_CHANGE_ALERT"), null)
};
}
2. Add created webresource to quote form and add quoteonload to functions that would be called during onload.
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