I bought Pixave soon after it first arrived in 2015 and was very pleased with it. Whilst some aspects of the interface are a little unintuitive, altogether the app worked well. Syncing via iCloud with my laptop worked fine and I invested in the iOS version too, although syncing the library there could take a while and seemed occasionally to repeat itself without apparent reason. So far, so good.
However, recently an important library of professional work refused to open correctly. No images appeared, no collections, nothing, yet the library was still 1,4GB in size. A backup version has the same problem so it seems clear to me something has probably gone wrong with the library database. I was alarmed as this work is valuable to me and I sent an urgent request for help to the dev, LittleHJ. It is now a week later and I have still had no response despite a repeat request. The Pixave website and general activity around the app seem to have quieted down a lot recently and I am wondering if the dev has maybe got tired of the app and has moved on to other things conveniently leaving loyal customers like me in the lurch. So my advice is to beware of keeping important data in Pixave or to have a non-Pixave backup if you do. In any event I will not be using Pixave any more. I am laboriously rebuilding my library from other sources and am cautiously looking around for a replacement from a reliable developer.