Account Management: Searching provides too many results in "Manage Tags" and "Search Groups"

Steps:

1. Go to Account Management
2. Click a client’s name
3. Click the “Manage Tags” button
4. Enter characters from the middle of an existing tag's name into the search box (for example, enter "bd" instead of "abcde")

Expected result:

Tags that don't start with given characters are not listed in the search results

Actual result:

Tags that don't start with given characters are listed in the search results.

For example, the tag "abcde" is listed for queries: "bcd", "e", "ce" (see attachment).

Additional information:

The same issue occurs for the search box in the "Search Groups" box in the "Groups" tab (see attachment).