Floating Static Route

Hi Team,
Was doing an Config on Aruba WLC:
OSPF neighbourship is all Good
Scenario is like that

WLC is connected to ASA and then ASA is connected to Internet + Core Switch as well

as Normal All Wifi and internet is getting access from ISP - But was looking for a Solution if Internet ISP is down then it will auto Pick the Connection from WAN ( Core Switch ) Via ASA.
have done all OSPF config on both devices - Ospf can learn routes as well
but when i do a Floating Static route (Default route) via diff Default gateway with higher AD

then upon checking Sh Ip route , it is picking default route from Static rouue even ISP is UP .

In between ASA and ISP - there is BGP connectivity
and between WLC and ASA ( I just config OSPF)

any Suggestion please

Thanks