Find the highest value from range, multiple entry and adjacent cells date

Hi

In the excel sheet, I have the date in J8:J9999 and Invoice number in the Column K8:K9999.

Invoice number having 4 series as below,
1 to 1000
1001 to 4000
4001 to 5000
10000 to 15000

Invoice number entry will be like this
1&2&3
1005
1006&1007&1008
4004
4005&4006&4007

I used a formula in R4 to find the highest value from 4000 to 5000 is
=AGGREGATE(14,6,K8:K9999/(K8:K9999>=4001)/(K8:K9999<=5000),1)

My expected value in R4 is 4007 (highest value between 4000 to 5000) but it is showing 4004 because it is ignoring to take 4005&4006&4007 entry.

How do I change the formula to get the 4007 in cell R4?

Note: The entry from 4000 to 5000 will be the year of 2019 entries only. I don't know how to get the highest value from this year entry as well as multiple entries too.

Please suggest the formula

Thanks in advance

Sincerely Yours
Anbuselvam K