InDesign Table of Contents Alphabetical Order Off Due to Spaces in Titles

For the company I work for, we have bibliographies using Table of Contents at the end of our book documents listing the articles referenced. One strange situation I learned about recently but has been a problem for past versions of the book documents is that the spaces don't seem to register into the alphabetical ordering of the articles. For example, "A Cause...", "Accuracy and...", "A Clinical...", "Activation and...", "Addressing Sleep...", "A Different", etc. I think the reason this issue wasn't spotted earlier is because most articles don't start with a single letter like A.

Is there a way to fix this issue, or is this a common problem? There are a lot of documents and article references that relate to the bibliographies, and the documents have some years in age now (roughishly 4). There are other small issues that the bibliographies can have, but I don't think any of those issues relate to this one.