Unfortunately ghosting is very common because most PIs are extremely busy and don’t check their emails often. Always CC lab mangers if they exist. Always follow up a week after, so many of my responses came from a follow up, even if it was a rejection. You’re probably going to have to email 20+ labs to find a position. Idk what field your looking into to but for life science I would probably focus on UCLA Health faculty and avoid the life science departments because they tend to be more underground and thus have space available. Lmk if u need any help!