HillTree_02 has negative Light Mass values, making Sum Tris in Statistics negative

I’m not sure this is the right place to post but I have been unable to find a similar situation with a simple google search. After opening the Statistics for a level with many trees, one of the two types of trees seems to have negative LM values while the other has positive LM values. I wonder first of all why this is happening and second if there is some effect on scaling within the project as a result of those actors having negative light mass data. Thanks in advance for anyone who can shed some light on this (pun may or may not be intended).