This evening I checked your Excel calculation with all numbers in your example and I came to the same results as you did using the Excel formulas. However, I found out that the total sum of all transactions from 18.10.2019 to 4.7.2020 add up to 726,19 and not to 700,4. So your investment lost around 26 of value (726,19 - 700 = value on Aug. 16, assuming that the value of 700,4 is correct), probably due to a loss in value.
It only proves that the negative results in Excel are correct.
Since PP shows positive results, there must be one or several mistakes in your data input in PP.