The best way to fix a clogged drain is to prevent it in the first place.
If the filter was clean, the clog might be hiding deeper. how to clear a blocked dishwasher drain
If the filter and sump are clean but water remains, the blockage is likely in the drain hose. This is the corrugated plastic or rubber tube that runs from the dishwasher to the garbage disposal or the sink’s drainpipe under the sink. First, disconnect the hose from the disposal or drainpipe. Place a bucket underneath because trapped water will pour out. Use a wet/dry vacuum to suck water and debris from the end of the hose. If you don’t have a vacuum, carefully blow through the hose (after sanitizing it) or use a long, flexible brush designed for this purpose. The best way to fix a clogged drain