Unfortunately this is how blank down works - it just keeps blanking in the column until it hits a new value, it doesn't care about records.
There are some other approaches that might do what you want, but to know exactly you'd need to say more about whether it is possible for a single record to have multiple values in the 'Amalgamation' column, and if so what behaviour you want in that case.
If there will never be multiple values in the record, or if you only need the list of values for the record but don't need to keep the values in their specific rows you can try:
In the 'Amalgamation' column use 'Join Multi-value cells', choosing a join character that won't appear in the column - e.g. a pipe | symbol
The first row in each record should now have a cell containing all the Amalgamation values
In the 'Amalgamation' column do a cell transformation to split the cell into an array based on the join character you chose, and then use the uniques function to get rid of duplicate values, then use join to create a string. e.g.:
value.split("|").uniques().join("|")
Given the data you have shown in your screenshot, this would work for this data. However, if you had multiple values in that column within the same record, you'd have multiple values in that cell.
If you have multiple values in the column within the same record and want to preserve their position in the right row, I think this is possible, but you need to something a little more complex. Let us know if the above is adequate, and if not, what the issues are and I'll try to help further.
Owen