Automate tab greyed out in online Excel

I've been developing a script in online Excel using the code editor on the Automate tab. The script takes the data in a table and sorts it into some other tables depending on a few fields. I then have a PowerPoint macro which picks up the data and sets up and populates some slides with the data.

I have returned to the Excel script today after a few days focusing on the PowerPoint macro and I cannot access or run my script as all of the buttons on the Automate tab are greyed out (see image below).

I can still run the script via a PowerAutomate flow - I just can't edit, run or even see it in the online app. While developing it, the buttons worked fine in Chrome but were greyed out in Edge browser for reasons I couldn't ascertain. Now they are greyed out in Chrome too.

Scripts and script sharing are enabled for all users in my organisation. We're using Office 365 A1.

Any help would be appreciated.