After updating Plesk on Linux server to Obsidian 18.0.47, the menu WordPress shows blank page instead of the WordPress Toolkit interface.
One of the following non-English locales - Greek (el-GR), Hebrew (he-IL), Russian (ru-RU), Ukrainian (uk-UA), Thai (th-TH) (and possibly Arabic (ar)) - is set as the default locale in Tools & Settings > Languages.
#PPPM-13735 "WordPress Toolkit now works correctly with all locales."
- Plesk Obsidian 29 September 2022
If update is not possible for some reason you may try the following