Split cells not working like before / can't adjust text spacing

Hi, I have 2 issues when editing my profile:

1. I can't seem to be able to split individual cells like before. On one of my tables the icon to split cells shows up in one cell but not the next cell.

Example shown below:

2. I can't seem to adjust the line spacing in a couple of my tables. I saw there was issue like this in a previous post which was resolved and I tried to follow the instructions on there but it hasn't worked for me.

Example shown in edit mode:

After saving the extra spacing appears. Shown below:

Hope this can be resolved for me. Thanks in advance.