this could be wrong because you did not provide full details making it impossible to determine what actually took place
you sold 600 but only bought 200 which means that you must have been holding at least 400 shares before the first sale
you sold 200 on 4/6. the gain/loss would be determined by reference to the first 200 shares you acquired
however, it would seem these were acquired at different times and at had different tax basis so some shares could have been sold at a gain while others at a loss
you sold 200 on 4/7. the gain/loss would be determined by reference to the second 200 shares you acquired
however, it would seem these were acquired at different times and at had different tax basis so some shares could have been sold at a gain while others were sold at a loss
on 4/21 you bought 200 shares this could trigger a wash sale for the first 200 you sold. however, only for those shares that were sold at a loss. so it's possible only 178 shares had a loss
on 4/22 you sold the 200 bought on 4/21. those shares, to the extent needed, would have had the disallowed wash sale loss add prorata to the same number of shares sold at a loss
US brokers are required to adjust basis for wash sales.
further clarification talk to the broker. they do at times screw up.
