Hi there,
Do you have a caching plugin installed? That could be a reason for the sidebar appearing in one browser but not in another, as caching can lead to discrepancies in how content is displayed.
If you can share the site link, we can take a closer look.
Hi Alvind,
Thank you for responding! No, I do not have any caching plugins installed.
Meanwhile I decided to recreate the problem in a more controlled fashion. Fortunately the website in question is still in early stages of construction, so I simply created a new WP installation and this time tracked, tested and documented customization step by step. So far there is no problem, I removed the sidebars first thing after activating the theme and they haven’t returned. Will report here with full details if the problem recurs.
No problem, glad to hear that!