[stumped]

so here is a shorter proof of issue:
tweaked the scene breaks a little more in calibre
then on tablet I Opened CC, deleted the book, connected to content server , downloaded the book , disconnected, read it - and the recent changes where not there i.e. a cached version had downloaded again
went back to PC, closed calibre, reopened it
then on the tablet, opened CC, deleted book, connected to content server, re-downloaded... changes were delivered OK
ps calibre version 3.3.1, i could install 3.5 and re-try but I see no mention ofd content server in changes for that version.
PPS I have had similar issues before , but I blamed myself for getting CC deletes and Moon reader deletes out of sync, i am pretty sure I have now proved its a content server caching issue. which will be frustrating when wanting to view the effect of book edits in a reader app. I want to be able to download a book, view it on device, tweak it in calibre library , delete from device, re-acquire it & recheck it....