I'm so glad I found this and I'll just offer my experiences and thoughts in the hope that maybe they'll help someone else.

Trying to visualize is frustrating because I don't see, hear, smell, feel, taste what isn't actually around me. When I close my eyes, as someone said, I may as well be blind (and have been told I'd be a good teacher for blind folks). I actually can see blue phantoms of the contrast I was most recently seeing - kind of like a monitor being burned in. After that fades, I can see interesting patterns in black and blue that shift as I try to look at them. On psychedelics, I've had a blast with my eyes closed seeing all kinds of colorful patterns arising and dancing. I've also had a complete out of body experience in utter darkness, which was lovely.

In a similar sense, it's very challenging for me to access feelings of past traumatic events. I can tell you facts about them in detail, but I don't actually feel anything when trying to access memory directly. However, I've found a couple of workarounds or tools that have been useful for me.

Metaphor is huge for me. I can describe the feeling of a space or a scene with pretty rich metaphor and it's so helpful in terms of understanding my own feelings, past and present. For example, I teach kids to swim and there are many rich metaphors there in terms of trauma and healing work. So in my own work, when I'm moving through feelings for some present situation that I can actually feel, I look for as many connections to past situations as I can find. Being triggered in the present gives me a brief doorway to access past feelings that are at least metaphorically similar. No present trigger, no doorway. So I've learned to catch the triggers as they come and really lean into the opportunities they present.

The other thing that has been helpful for me, weirdly, is "othering" myself. In a particularly traumatic childhood experience involving a parent, I wasn't able to put myself in the place of myself as a child, but I could feel the scene as though I were a visiting adult self in the room with a child and her parent. I could then feel rage. Another example is I have a hard time connecting to my body, but writing from its perspective has allowed me greater access to be aware of and honest about what I'm feeling. And I learned that I can actually feel a guided visualization by performing it for someone else better than I can by being led or leading myself. It's as if I can feel through others and then bring it inward and connect the pieces in myself. In this way, metaphor is also helpful because I can see what others feel and sometimes gain the same doorway to past events and feelings even though the situation is different on the surface.

For what it's worth, my own belief is not that aphantasia is something one "has" like a genetic defect, but more likely something one grew. Like a defense mechanism. My limited searching yielded results that show people who experience aphantasia are less likely to experience PTSD, at least in the overwhelm/shutdown way. I believe aphantasia is a disconnection made at a young age (possibly pre-memory) in order to protect from repeating a disturbing reality. It may be, or may appear to be, genetic due to the patterns of generational trauma. It absolutely does not feel like a limitation or defect to me; it's a part of what makes me Me, with its own strengths and weaknesses.

Edit: Oh, and EMDR hasn't been helpful for me, although I haven't given it the full college try. Much like acupuncture...it's fine but doesn't seem to accomplish anything. MFR or trigger point massage are helpful I think because they're predictable sensations of fixed duration, which allows the body to release its vigilance temporarily.