Steps to reproduce:

1. Create host A, B, C;
2. Open each hosts item creation form in a new browser tab;
3. Create item under host A;
4. Press add;

Result:
The message that Item is added is displayed;
You're redirected to the previously opened host C item form
URL is not specified that it should be either host A or B, but just: items.php?context=host
Expected:
The message that Item is added is displayed;
Redirected to the list of host A items, the URL properly displays information of host A
items.php?filter_set=1&filter_hostids%5B0%5D=(YourHostID)&context=host