Let $M$ be a compact connected manifold, $X\subset M$ a closed subset, and $f:M \times [0;1] \to M$ an isotopy such that each $f_t:M \to M$ is fixed on some open neighborhood $N_t$ of $X$, but there are no assumptions on the "size" of $N_t$ and "continuity" or "uniformity" of those neighbourhoods in $t$.
Is that true that there exists a neighborhood $N$ of $X$ such that all $f_t$ are fixed on $N$?
This question can be reformulated as follows. For a homeomorphism $h:M \to M$ its support is defined as $$ supp(h) = ( x\in M \mid h(x) \not= x ) \equiv M \setminus Int(Fix(f)), $$ where $Fix(h)$ is the set of fixed points of $h$, and $Int(Fix(h))$ its interior. (Please replace above the round brackets by curly ones: they are not displayed here).
Notice that the above isotopy induces a level-preserving homeomorphism $F:M\times [0;1] \to M \times [0;1]$, $F(x,t) = (f(x,t), t)$. Then $supp(f_t) \times \{t\} \subset supp(F)$, whence $\mathop{\cup}\limits_{t\in[0;1]} supp(f_t) \times \{t\} \subset supp(F)$ as well.
The question is thus whether $$ \mathop{\cup}\limits_{t\in[0;1]} supp(f_t) \times \{t\} \stackrel{?}{=} supp(F).$$
The problem is that the support of a homeomorphism is not stable under small perturbations. Perhaps some additional assumptions on $M$ should be made.
Also, note that $supp(f_t) \times \{t\}$ is closed in $M\times[0;1]$. On the other hand, the family of such sets is (a priory) not locally finite, and therefore one can not guarantee that their union is closed. But, if $A:=\mathop{\cup}\limits_{t\in[0;1]} supp(f_t) \times \{t\}$ were closed, then since $A\cap (X \times [0;1]) = \varnothing$, compactness of $X \times [0;1]$ would guarantee that there exists a neighborhood $N$ of $X$ in $M$ such that $A\cap (N \times [0;1]) = \varnothing$. Then $N$ will be the required neighborhood.