Lobanova notes that Roslavets lists 6 violin sonatas in the worklist he compiled in 1940, and that 5 of them had either been found or could perhaps be accounted for (she refers to the preface of the edition of the 2nd violin sonata, which I should, I admit, go read); no reason is given why the 6th is not, say, still lost and the sonata enclosed not some other work, e.g. a work of youth?, that Roslavets simply did not list...