If you by mistake place a holder from IQOS 3 or IQOS 3 DUO to a IQOS 2.4 Plus pocket charger, the LED controls will flash, but the holder will not be charging.
You can use the charging adaptor from previous versions. The USB charging cable for IQOS 3 DUO and IQOS 3 DUO devices have a USB-C port, which is different from the port on IQOS 2.4 Plus.