Initialization and saving problems for FX chains

[SanderVocke]

In a project with multiple FX-enabled tracks, sometimes only one FX track will load and activate, and all other tracks will remain "red" (uninitialized).

Then, when opening the Carla GUI for the only track that does work, suddenly all the others start working.

A side effect of this is that as long as track FXs are not initialized, they cannot serialize their state, leading to timeout errors and incomplete data when trying to save the session.

Attached is a project to test with.

carragana.shl.txt

After some investigation it turns out that most of the Carla instances are stalling on:

m_state_iface->restore(
                lilv_instance_get_handle(m_instance), LV2StateString::retrieve,
                (LV2_State_Handle)&s, LV2_STATE_IS_POD | LV2_STATE_IS_PORTABLE,
                features);

Maybe investigate with a debug version of Carla.