Not sure I used Piviti, but used Shortcut, Openshot and Kdenlive. Kdenlive wins hands-down in stability and least amount of UI glitches.
(I recall that these interestingly share the same video editing backend, just the integration is different?)
(I recall that these interestingly share the same video editing backend, just the integration is different?)
Last time I looked, they were all using MLT [0] for the backend.
It's the only one that does not have a 50% chance of segfaulting on every click. Not an exaggeration.
Pretty much the only viable solution for FOSS video editing though I have yet to try Blender.