Bob you've never had problems posting a X (formerly Twitter) link before, what happened this time. I just click the three little dots on the top right and chose embed post, then copy code and then here on the skybox choose the media icon and paste the code previously copied to the clipboard and voila. The magic of the software strips everything but stuff between the [ brackets labeled MEDIA and voila.
I use the X app. I press an icon on the bottom right hand screen on X to copy the address and then paste it into the media and then press the embed button. Used to work fine but now it rejects every URL I paste into it.
I haven't used the X App, have you tried pasting it into the "link" icon? I do that with Youtube where I copy the address.