Search queries against Azure Search might fail when run in a geo-replicated configuration. This happens because the Index-Catalog is created only for the first search service. Therefore, the search does not work if the first service becomes unavailable.
To resolve the issue, download and install the hotfix compatible with the affected product version: Upgrade Sitecore XP instance to 9.3.0 or higher (recommended). For Sitecore XP 8.2.7: SC Hotfix-442234-1 Sitecore.ContentSearch.Azure 1.1.4.zip For Sitecore XP 9.1.0: SC Hotfix-330943-1 ContentSearch.Azure 4.0.0 For Sitecore XP 9.2.0: SC Hotfix 418196-1 Sitecore.ContentSearch.Azure 5.0.0.zip Be aware that hotfixes were built for specific Sitecore XP versions, and must not be installed on other Sitecore XP versions or in combination with other hotfixes. In case any other hotfixes have already been installed on a certain Sitecore XP instance, send a request for a compatibility check to Sitecore Support. Note that the ZIP file contents need to be extracted to locate installation instructions and related files inside. The hotfixes must be installed on a CM instance and then synced with other instances using standard development practices.