I would remove them from the glasshouse. It traps humidity so it makes the media dry out slower. Succulents want to dry faster and not remain too soggy, and good airflow helps too.
Also, the older, lower leaves normally do drop off as the plant ages. If those plants are already rooted, then maybe it is just dropping the old ones. At times, it is dropping them off as it slowly tries to redirect its resources to new growth, so give it time adjust and hopefully newer growth will form at the nodes, at the base or near the tip.
If these are new cuttings, warm temps with part shade conditions will work good for them as it tries to form new roots.
