Issues with Kan Cassette Resolution using pCP20?

Hi all,For a rotation project, I need to flip a Kan cassette out of its site on the shigella genome. I've used FLP before with no issues in e. coli, and the lab uses this method frequently. Recently, it's stopped working. We've made new preps, checked plasmid size, etc. but the cassettes will NOT flip out. We use the temp-sensitive pCP20. The site has been sequenced, so the FRT sites are definitely there.The method we use is as follows:-Electroporate plasmid into hypercompetent shigella. Recover at 30C in SOC for 1 hour, plate on TSB+Congo Red+Amp and grow ~24h at 30C. I get 30-50 colonies for this step.-Restreak on TSB+CR and grow at 37C to induce FLP and cure plasmid.-Patch onto Kan, Amp, and antibiotic-free to test sensitivity. We usually have no problem curing the plasmid.I've tried shifting to 42C, which speeds up plasmid loss but doesn't seem to have affected Kan resolution. I might try growing in liquid, since a few scattered protocols suggest that. I'm not the only one in the lab struggling with it. Any suggestions would be appreciated!