Make sure all correspondence is in writing so you have a record. It is unlikely that sanctions would be granted (at this time) by the judge but if the issue(s) continues you may be able to get them. Good luck.
1. Confirm the agreement in writing to the opposing party or attorney.
2. Give them a specific time to either sign off on the stipulation which was already agreed upon or advise them you will seek enforcement from the Court.
3. If they dont file the signed papers, fiel a Motion to Enforce. Set it according to the Judge's rules, each Judge has their own rules.
4. Once the matter comes for hearing, it will be up to the Judge to decide when and how it gets ruled on, the other party can only delay it so long.
5. The purpose of the stipulation will matter and determine how it is handled as well. Seek counsel's assistance to analyze this. Call me 305 377 1505 or email email@example.com and I will try to help, assuming you are not already represented. If you have an attorney seek their advice.