Reproduction steps:

1. Open "EcsFiltering.zip" project
2. Enter Play Mode
3. See Console output

Expected Result:
"Unique shared strings count 11: ["" "0" "1" "2" "3" "4" "5" "6" "7" "8" "9"]
Entities with string value="0": 2 count
Entities with string value="3": 1 count
Entities with string value="unexpectedValue": 0 count"
Actual Result:
"Unique shared strings count 13: ["" "0" "1" "1" "2" "3" "4" "5" "6" "7" "8" "9" "unexpectedValue"]
Entities with string value="0": 2 count
Entities with string value="3": 0 count
Entities with string value="unexpectedValue": 0 count"

Reproduced with: 2019.1.0a6, 2018.3.0b8, 2018.2.14f1, 2018.2.0f1, 2018.2.0b10
Did not reproduce on (ECS doesn't work): 2018.2.0b9, 2018.2.0b1, 2018.2.0a1, 2018.1.9f2