The REPEATER, as all the products, must respect the radio regulations and so the Duty Cycle when it repeats frames. If too many frames are sent by the products, the REPEATER will repeat only the number of frames authorized by the regulations. Consequently, it will not repeat all the message, that can explain why some frames are lost or not repeated.
If you must repeat more than 6 frames per hour (whatever the number of device), you have to deactivate the Duty Cycle of the REPEATER configuring the S304 register to 2 (Duty Cycle deactivated) through AT commands or via downlinks. This option is currently not available through the Repeater App put at your disposal by adeunis.
Note: Deactivation of the Duty Cycle results in a violation the regulations in force. Be informed that the responsibility is transferred to the user of the product.