Is it no longer possible to update tags on posts in Blogger?

Because quite a lot of my blogposts are list-based I often update them with more recent information (eg the ones listed on the right including the science communication jobs pages and I'll be updating the one on open air cinemas when the venues publish their listings) and whenever I click the 'Publish' (or 'Update' button when it's an edited post) I get a warning sign as shown below.

The warning suggests that I have some illegal ampersands in my tags, which I don't. It is not possible to click 'ignore' and update anyway, the system just doesn't permit it. This means I have to remove the tags and put them in the body of the post, which is a ridiculous way to handle metadata.

I can't be the only one experiencing this? Or perhaps it's a browser thing. I'm using Chrome with Win 7 Starter eidtion at home if that helps (click on the Start button and type winver into the search box and it brings up info about your windows version).

The title of this post is a little misleading - I don't actually want to update the tags but the post. It's the tags which are causing a problem (as yet unidentified) with the process of updating the post itself.

There's a red banner at the top announcing a problem with the tags which are on the right hand side, I've had to remove them from this post and put them in the body.

While we're at it, I could do without the intrusive little 'Composition editor' announcementette popping up uninvited and making it harder to see what I'm typing. Other than that, very happy with Blogger, just very very confused that tagging is now a problem. I've added one tag to this post, let's hope it goes through.