Someone else will come on here and rightfully correct me - my gps knowledge is a bit rusty...
RAIM is only for non-WAAS recievers. Since the IFD 440 is a WAAS unit, corrections are continuously broadcasted and do not require a RAIM prediction calculation to insure integrity. Relevant portion copied and pasted below from FAA Aviation news publication.
Briefly looked at NOTAMS in the area on foreflight, but didnt see anything relevant to outages.
Noticed your approach location is next to a MOA - unsure if local interference can affect only WAAS performance?
No answers, just thinking out loud
AIM 1-1-20 describes the Wide Area Augmentation System (WAAS). With WAAS, strategically positioned ground-reference stations monitor GPS satellite signals and correct any errors in the data that can result from atmospheric anomalies. This “cleaned-up” version of GPS data is sent back to the GPS satellite network and then rebroadcasted. A WAAS-enabled GPS receiver (TSO-C145 or C146) uses this version of the GPS signal to provide more accurate position data, FAA’s RAIM prediction model uses assumptions about generic aviation grade GPS receiver performance, so your specific receiver may be better. The model uses a generic RAIM algorithm to predict a horizontal protection level (HPL), considering the current and scheduled status of GPS satellites. The HPL is then compared to the alert limit for the phase of flight: en route (2 NM), terminal (1 NM), non-precision approach (0.3 NM), to determine availability. If the HPL is predicted to be greater than the alert limit, an outage of service capability is indicated. January/February 2010 FAAAviation News 25 making RAIM prediction unnecessary in these units. In addition to providing the correction signal, a WAAS geostationary satellite provides an additional range measurement to the GPS receiver, improving the availability of GPS by providing, in effect, an additional GPS satellite in view