Hi Stewart @UnkaStew
After a reboot and you are still encountering issues with RapidWeaver 6.3.8, download the full install here and reinstall.
If that does not resolve the issue, perhaps you have an out-dated Plugin or stack installed that may be causing an issue or some issues with your OSX installation…
Something to watch for, if you use a disk cleaning utility like MacKeeper or the like, these remove important files if you’re not 100% sure of what you’re doing and can cause OSX and APP issues, so if you have any of those, uninstall them, same applies for app uninstall utilities, system preferences enhancement utilities, etc.
To do first aid in OSX 10.11.x
Close ALL open apps and background/helper services that you can (Dropbox, 1Password and the like)
Utilities -> Disk Utility
Select the desired HDD
Click the First Aid button
Go to bed lol and check in the morning (depending of HDD size of course)
Reboot when finished and check your RapidWeaver installation again. (you may have to once more install RapidWeaver but hopefully not.)
Lastly, if this does not resolve the issue, I suggest a reinstall of OSX as the last step in issue resolution, BE SURE TO DO A BACKUP FIRST.
PS: I know you asked this in the support system but am not going to interfere with Stuart or cause cross-posting so am answering here and this thread may help other users so killing 2 birds with 1 stone…
Secondly, Stuart would like a zipped copy of the .rw6 file which is the RapidWeaver Project file, not the exported site if I understood your comment correctly in the support system. You can compress it using finder, find the project file, CTRL+Click it and choose Compress “filename.rw6” this should create a ZIP of the project file (filename.zip), this is what Stuart requires…
Hope that helps