AU plugin FAILS validation in Logic 10.7.7 on M1 but PASSES on IntelMac

macOS
1

I just released an AUv2 plugin and users are now reporting it FAILS validation in Logic 10.7.7 on Ventura (M1/M2/Arm) - but yet it runs without issue in Logic (as “Incompatible” plugin) as well as other DAWs on the same system.

Meanwhile, it PASSES all tests and works in Logic 10.7.7 (as well as other AU compatible DAWs) on Intel Mac.

Here is the validation failure section from Logic 10.7.7 on M1:

Reported Channel Capabilities (explicit):
      [1, 1]  [2, 2] 

Input/Output Channel Handling:
1-1   1-2   1-4   1-5   1-6   1-7   1-8   2-2   2-4   2-5   2-6   2-7   2-8   4-4   4-5   5-5   6-6   7-7   8-8
X                                         X                                                                       

# # AudioChannelLayouts (2), Input Scope:
ChannelLayout is Writable: T
The Unit publishes the following Channel Layouts:
  0x640001, 0x650002,

Is Audio Channel Layout Available:
Mono    Stereo  Binau.  AU_4    Ambi.   AU_5    AU_5_0  AU_6    AU_6_0  AU_7_0  AU_7_0F AU_8    AU_5_1  AU_6_1  AU_7_1  AU_7_1F
X       X                                                                                                                       
ERROR: 4099 IN CALL Problem with initial Channel layout state

* * FAIL
--------------------------------------------------
AU VALIDATION FAILED: CORRECT THE ERRORS ABOVE.

If I chose to override the validation failure and “run as Incompatible plugin” - the plugin works and without any apparent issue.

I’m using the same I/O configuration I’ve used in other plugins that have no issues (“1-1 2-2”).

So, what’s wrong here? The only difference I see in the failed vs. pass reports is “ChannelLayout is Writable:” shows True in the failed report while in the other reports where it passes it shows False. Is that the issue? If so, what’s causing it and how do I fix it?