Possible fix

src/main/java/io/ebeaninternal/server/query/CQueryBuilder.java

@@ -265,7 +265,9 @@ class CQueryBuilder {
     if (!countDistinct) {
       // minimise select clause for standard count
       if (manyWhereJoins.isFormulaWithJoin()) {
-        query.select(manyWhereJoins.getFormulaProperties());
+        // FIXME: we join the strings here and on the other side we split them again
+        // this is not yet optimal
+        query.select(String.join(",",manyWhereJoins.getFormulaJoinProperties()));
       } else {
         query.setSelectId();
       }