Problems with Key Figure and Drilldown

Good day to you, experts. Several of our reports are required to include a key figure which shows a percentage value. The Query must show something similar to the following (please ignore the "-"):

-

Total Products-- -Products Sold --

Percentage sold

Shop A / Jan--

40%

Shop B / Jan--

100%

Shop C / Jan--

30%

TOTALS / Jan--

56.66%

We can see this information for all months. As you can see, it shows the "Shop" Characteristic as well as the Calendar Month (or year, or year/month). The information is updated monthly. The percentage total is calculated as average.

So far so good. The problem is that whenever I take away the Calendar Month characteristic (in order to see this information summarized and not detailed by month), the "Percentage Sold" Key Figure (which is loaded along with the rest of the information, not calculated in the Query) shows strange data, something like this:

-

Total Products-- -Products Sold --

Percentage sold

Shop A--

220%

Shop B--

454%

Shop C--

150%

TOTALS--

274.66%

So as long as I keep the most detailed information on the table, it is displayed correctly, and as soon as I take away any of the details (it also happens with the Shop characteristic), the percentage sold displays wrong data. I have tried displaying individual values differently. I also tried using a formula to calculate the percentage sold, which appeared to solve this issue, but after testing it I found that the data on "TOTALS" was incorrect both with and without the monthly detail. This issue has become quite urgent as we are supposed to publish these reports very soon.

Any ideas for solving this issue?