Buffer size requirement?

AV Linux2016 64bit install, Ardour log tells that some LV2 plugins are ignored (or not loaded, can’t remember which) because buffer size requirements cannot be satisfied.
Otherwise systems runs finely, 8 gig+dual core and 256 buffer and 2 periods on Jack.

It means that the plugin reports a requirement for the buffer size passed to it always having the same value. This is not possible given Ardour’s internal engineering design (specifically for automation and looping), so we refuse to load/use such plugins.