A friend once posted a picture of his workplace development team of perhaps 15 people and almost entirely the team was composed of males under 40. I was shocked. Shocked to see it and shocked to see the friend was posting it proudly without any hint of him seeing the message it was conveying to gender and age minorities. The message is “We know what works and you are not part of that."
I am sure many potential contributors fade away with some sort of feeling that inclusivity didn't include them.
I don't know of any studies that try to identify the reasons people bail out.
In my estimation inclusivity is predicated suchly:
We are each human, this is not a meritocracy, it is an open source, open mind, inclusive, all embracing creative community, where, when a unique individual begins to make his or her holy, or innovative disruptive, offering into the circle, we do not immediately jump to evaluate that offering against what has come before, or where our business plan is heading, or even against what makes sense to us right now, we stop and listen and actively question, without any sense of refutation, to find out how that offering is perceived in the mind of the one who is offering it, and how that unique offering might benefit the community, and the product.
To the extent we react against the unfamiliar mind, or to the extent we unconsciously expect the tentatively included ones to morph their being towards the way things have been done before, or towards any currently dominant culture, welcoming for example women who can adopt a male attitude, or an older person who Millennialises their old-school mind, or a solitary workflow hermit who can choose to adopt teamspeak, or <name your currently deliberately or unconsciously excluded minority> who can learn to be <more like us>, we are exclusive with a presentation layer garment of inclusivity, not inclusive in essence.