[Resolved] 403 error when creating campaigns

I’m running phplist 3.3.4 on a shared server. It’s been working fine - last campaign created and sent on 31 October. However today when I try to create a campaign I get an error message when I try to change tabs

" Forbidden
You don’t have permission to access /phplist/admin/ on this server.
Additionally, a 403 Forbidden error was encountered while trying to use an ErrorDocument to handle the request."
I seem to be able to do everything else - including accessing and changing settings.

I don’t know if this is a phplist problem or a hosting problem - can anyone offer any advice please?

(I noted a previous forum entry on this topic logged on Aug 8 by Phil Catlin but didn’t see any responses to this.)

Now resolved. My hoster advised: "I believe this may be due to recent mod_security updates on the server.

I have made some changes to the mod_security ruleset." This seems to have done the trick.