For 10/30/2020, over 3.15M ballots are returned in WA with 37,696 challenged. Almost 24,863 of these challenges are signature not matching . Another 5,141 are missing signatures. Voters should visit https://voter.votewa.gov and check their ballot status. For ballot status other than "Accepted", voters may want to contact or visit their county election department websites found at https://www.sos.wa.gov/elections/auditors.
For turnout, please see https://www.sos.wa.gov/elections/research/ballot-return-statistics.aspx 10.1 % or 318,444 of all returned ballots were by voters who last voted in 2018 or earlier. 251,000 of all returned ballots were by voters whose 'LastVoted' field is "NA". These numbers suggest an increasing number of 'first time' and 'low propensity' voters in this very high turnout election. And that's significant since it suggests that by Tuesday this group may well be 20% or more of the electorate:
round((318444 + 251000) / 3155177,3) * 100 =
18 percent of returned ballots are potentially from 'low propensity' or 'first time' voters.