Portfolio. Not updating

I have 6 portfolios set up and they function well during market hours. But after market close, all data is missing except for the number of shares that I hold, on 10 - 60% of my stocks. On some days the data is missing for 5 or 6 stocks, and on some days it is 20 stocks. This started about 10 days ago. The problem is the same on my PC and iMac.