Unfortunately, not all Cherry MX stems are made equal. The stem cross for each switch type varies heavily. You will find that the precisely machined Rama Works CNC machined keycap will fit perfectly on some switches, and loosely on others. To account for this variance, the stem on the Rama Works cap was designed to fit on most switches but may require adjustments to fit tightly.
Rama Works has a guide on their website to help you correct this.