Translations not working in v3.4.8 (that work on switch back to v.3.2.13)

Hi,

I’m experiencing an issue where the string translations in a client site stopped working when we updated from 3.2.13 to 3.4.8. Meaning, string translations don’t seem to work at all in the site for v3.4.8 but immediately start working again if I go back to v.3.2.13.

I can’t share any URL details here but I’m wondering if this rings any bells? Any idea what might be going on here? Any advice, pointers or leads you could provide would be greatly appreciated.

Since there are security fixes in the intervening versions I’m anxious to the the latest version working of course.

Thanks in advance,

Michael.