Thanks!
What was unclear (at least to me) from your first post is that a "large number" of Byzantine mss of Revelation, admittedly reflecting a fairly consistent textual tradition, did include the commentary by Andreas (this might sound somewhat clearer in the German N-A Einführung, "die grosse Zahl der Handschriften mit dem Apokalypse-Kommentar des Andreas von Caesarea zusammen"). So they do count as a sizeable section of Byzantine witnesses (I should have started my quote earlier: "The manuscript tradition for the Book of Revelation differs greatly from that of the other New Testament writings. [Cf. J. Schmid, Studien zur Geschichte des griechischen Apokalypse-Textes (3 vols., Munich 1955/1956).] One peculiar characteristic is the division of the Byzantine Majority Text into two distinct textual traditions" ["MA" and "MK"]). And, btw, from this perspective it is not so surprising that one of those manuscripts found its way into Erasmus' hands...
I suppose that this "peculiar" situation is due to the particular status and nature of the book, which was better received in the Greek church with an interpretive commentary (?).