The following effects aren't applied to the MULTI I/O section. This is part of the unit's specifications and not a malfunction.

・ SEND

・ BEAT FX

　DELAY, ECHO, PING PONG, SPIRAL, REVERB, TRANS, FILTER, FLANGER, and PHASER.

However, if [MULTI I/O] is selected with the input selector switch, the unit's built-in FX will be applied.

For details, see the block diagram in the specifications section of the Instruction Manual.

You can read the Instruction Manual [here].