
Because of the design architecture of V2, the test signal is switched on and off at a few kHz. Crystals can settle slower than that, so results will be inaccurate when measuring crystals.
This applies to measuring crystals only, and doesn't affect SAW or other types of filters. This is also in the documentation and product descriptions.
The V2 Plus and V2 Plus4 firmware are actively maintained but the focus is on bugfixes and stability, and the changes required to support measuring crystals is tricky and experimental, so it will be released as a special firmware rather than be integrated in the default firmware. Officially, if you need to measure crystals, the recommendation is to use a V1 nanovna (edy555 version) or nanovna-f. I can assure you that the upcoming release of V3 does not mean V2 Plus/Plus4 are left unmaintained, in fact we still consider V2 Plus4 the main product (V3 is not expected to sell very much).