Cannot tune a third-party tunable DWDM SFP+ from the Arista CLI: wavelength never changes

The poster had an Integra Optics tunable DWDM SFP+ (1528.77-1566.72 nm, 96 channels, 80 km, 10G, sold as Calix/Arista compatible) in an Arista switch. Changing the frequency and configuring the ITU channel through the Arista CLI had no effect: the module kept reporting the same wavelength. The question was whether third-party tunable optics can be tuned through EOS at all or whether the module has to be pre-tuned by the supplier.

• Hardware: Arista switch (EOS)
• Transceivers: Integra Optics tunable DWDM SFP+ 80 km 96ch
• Form factor: SFP+

Symptoms / messages:

wavelength unchanged after channel configuration
tunable optic not tuning