I select in Host Groups view some group with more than 1000 hosts. In view "CONFIGURATION OF HOST GROUPS" I can see in left table all group hosts (1590) (search_limit=2000). But when some group was chosen in selector "Other Hosts | Group"(right), left list of host was limited to only 1001 hosts. When the same group was chosen - hosts above 1001 are listed in right list (like not included in this group). Adding new host in group show error:
[ CHostGroup::massUpdate ] One of the Objects is left without Hostgroup
T.e. saving try to remove hosts above 1001 from this group and fail because these hosts not included in other groups.
Version 1.8.6 not have this bug.