OK, so the problem is that these manual import or export attempts sometimes fail, indicating an error?  What is the error number?

Hello again, Andy.

When you refer to trouble syncing, which of the following do you mean

• Manually (In BookMacster, manually click in the menu: File > Import… or [i]Export...)
• Automatically (Change bookmark(s) in a browser, expecting that syncing the change to other browsers will occur automatically.)

Keeping thoise browser windows open will be tedious and fragile for you.  It is sad that this bug (not messaging with other apps unless a browser window is open) was introduced into Chrome a year or two ago and the Chrome team has acknowledged it but no apparent action for over a year.  Clicking on that link in the previous sentence and adding comments might help.

Hello, Andy.

Thank you for contacting us.

I just realized that syncing different personas (profiles) in the same browser is going to be challenging, because recent changes in Chrome caused us to disable importing/exporting while the browser is not running in a given profile, and also a recent bug in Chrome, which then spread to the other Chromium-style browsers, that causes syncing with a given profile to fail if there is no window open in that profile.  Failures will result in very annoying error notifications.

I think that, for any browser in which you are syncing to or more profiles, you may need leave at least one window open in each profile/persona.  (Minimized to the Dock counts as "open".)

Please reply and tell me how many profiles in what browsers you want synced, and which one is your "Reference" persona.  Also tell me what you think about leaving browsers running and windows open.  I'll be able to respond more specifically.

Normally, for syncing among the internal bookmarks of web browsers, you do not use New  bookmark is landed from browser.  The word landed in this context means that you manually sent the bookmark directly from the browser to BookMacster using BookMacster's Status Item, Dock menu or global keyboard shortcut.

Actually, you should really consider doing that, using BookMacster directly as we call it, instead of adding bookmarks to browsers' built-in bookmarks and relying on BookMacster to sync.  Syncing is always more problematic, and with different profiles in the same browser nowadays, even if there is a way to make it work, it is going to be really fragile.  This is where you would use New  bookmark is landed from browser.

Again, all the trouble comes from persona/profiles in the same browser.  If you'd only have one persona/profile in each browser, appropriately setting one Import and many Export checkboxes as you discussed would work.